U.S. Department of the Interior 

Bureau of Land Management 

BLM Alaska Open File Report 106 

BLM/AK/ST-06/016+6501 +020 

April 2006 

A Literature Review and Synthesis on the Effect 

of Pipeline Height on Caribou Crossing Success 

Brian E. Lawhead, Julie P. Parrett, Alexander K. Prichard, and David A. Yokel 
The BLM Mission 

The Bureau of Land Management sustains the health, diversity and productivity of the public lands for the 

use and enjoyment of present and future generations. 

Cover Photo 

Caribou graze near elevated pipelines in the Kuparuk Oilfield, northern Alaska, after reaching coastal 

mosquito-relief habitat on 1 0 July 2002. Photo by Brian Lawhead, ABR, Inc. Copyright ConocoPhillips Alaska, 

Inc. 

Authors 

Brian E. Lawhead and Alexander K. Prichard are Senior Scientists at ABR, Inc. Environmental Research 

and Services in Fairbanks, Alaska. Julie P. Parrett is a Research Biologist at ABR in Fairbanks. David 

Yokel is a wildlife biologist at the BLM Fairbanks District Office in Fairbanks. 

Disclaimer 

The mention of trade names or commercial products in this report does not constitute endorsement or recommendation for use by the federal government. 

Open File Reports 

Open File Reports issued by the Bureau of Land Management-Alaska present the results of inventories or 

other investigations on a variety of scientific and technical subjects that are made available to the public 

outside the formal BLM-Alaska technical publication series. These reports can include preliminary or incomplete data and are not published and distributed in quantity. 

The reports are available while supplies last from BLM External Affairs, 222 West 7th Avenue #13, Anchorage, Alaska 99513 and from the Juneau-John Rishel Minerals Information Center, 100 Savikko Road, 

Mayflower Island, Douglas, AK 99824, (907) 364-1553. Copies are also available for inspection at the Alaska 

Resource Library and Information Service {Anchorage), the USDI Resources Library in Washington, D. C., 

various libraries of the University of Alaska, the BLM National Business Center Library {Denver) and other 

selected locations. 

A complete bibliography of all BLM-Alaska scientific reports can be found on the Internet at: 

http://www.ak.blm.gov/affairs/sci_rpts.html. Related publications are also listed at 

http://juneau.ak.blm.gov. 
A Literature Review and Synthesis on the Effect 

of Pipeline Height on Caribou Crossing Success 

Brian E. Lawhead 

Julie P. Parrett 

Alexander K. Prichard 

David A. Yokel 

BLM-Alaska Open File Report 106 

April 2006 

U. S. Department of the Interior 

Bureau of Land Management 
ABSTRACT 

The effects of elevated pipelines on the movements of caribou (Rangifer tarandus) in Alaska 

have been studied since the late I 960s. The recent expansion of oil development west of the 

Kuparuk Oilfield raised the issue of pipeline height to prominence for local residents ofN uiqsut 

and other North Slope villages and prompted this review of the literature. Linear infrastructure 

such as pipeline/road corridors can act as obstructions that impede caribou movements but do not 

act as complete barriers unless they are physically impassable, such as large-diameter pipelines 

on or near the ground. Most of the pipelines in the Prudhoe Bay Oilfield were constructed in 

the 1970s before the minimum height of 1.5 m (5 ft) above ground level was stipulated by the 

State of Alaska. Older pipelines elevated 0.4-1.1 m above ground level in the Prudhoe Bay field 

constitute barriers to caribou crossings in the absence of crossing ramps. The available data on 

pipe-height selection by caribou demonstrate that pipelines elevated to the minimum height of 

1.5 mare high enough to accommodate crossings by caribou during snow-free periods. The 

limited data on pipeline crossings by caribou in winter indicate that pipeline heights in the range 

of2. l-2.5 m (7-8 ft) are more likely to be used by caribou than are lower heights. Because of 

a tendency for more snow to accumulate beneath lower pipe, elevating pipelines higher than 

1.5 m will decrease the risk of reduced clearance between the snow surface and the bottom 

of pipelines, especially in severe winters. Research in northern Alaska oilfields has confirmed 

that the most important factor affecting caribou crossing success at pipeline/road corridors is 

traffic on nearby roads. The combination of high-traffic roads ( 15 or more vehicles/hr) adjacent 

to pipelines elevated to the minimum height of 1.5 m created a synergistic effect that reduced 

caribou crossing success. Hence, to be as effective as possible, elevated pipelines should be 

separated at or beyond the recommended minimum distances of 122-152 m (400-500 ft) from 

roads. Separating roads from pipelines also achieves the important purpose of eliminating 

snow drifts under pipelines next to roads. In addition to traffic, other factors that confound 

evaluation of pipeline-crossing success by caribou include differences in infrastructure and 

study design, caribou group dynamics, insect harassment, season, habitat, topography, and 

habituation. Needs for further information regarding the effects of pipeline characteristics on 

caribou crossing success include the adequacy of 1.5-m-high pipelines in winter (to supplement the scant data available); the effects of habituation; the effects ofreflectivity of pipeline 

sheathing and other potentially confounding factors not yet investigated, such as auditory and 

chemical stimuli; and the adequacy of the 1.5-m minimum height for crossings by subsistence 

users on snowmobiles. 

ACKNOWLEDGMENTS 

Funding for this project was provided by the Bureau of Land Management's Arctic Field 

Office. Stephen Murphy of ABR reviewed the draft report and provided valuable insights from 

his experience studying oilfield impacts on caribou. Caryn Rea, with ConocoPhillips Alaska, 

Inc., granted permission to use digital map layers of oillield infrastructure and photographs 

of elevated pipelines taken during research funded by ConocoPhillips Alaska. Dortc Dissing 

prepared the map figure. Lincoln Panelt assisted in acquiring literature. 
CONTENTS 

Abstract ................................................................................ i 

Acknowledgements ....................................................................... i 

Introduction ............................................................................. I 

Methods ................................................................................ 3 

Review and Synthesis .................................................................... 3 

Analysis of Crossing Success ............................................................. 3 

Pipeline Height ....................................................................... 5 

Pipeline Height Below 1.5 M .......................................................... 6 

Pipelines Elevated 1.5 M And Higher ................................................... 7 

Other Factors Affecting Crossing Success .................................................. 10 

Infrastructure Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ................ 10 

Crossing Ramps ................................................................... 11 

Traffic ........................................................................... 12 

Group Dynamics ................................................................... 12 

Insect Harassment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... 13 

Season ........................................................................... 14 

Habitat And Topography ............................................................ 14 

Habituation ....................................................................... 15 

Conclusions ............................................................................ 15 

Research Needs ....................................................................... 16 

Literature Cited ......................................................................... 19 

Figure 1. 

Figure 2. 

Figure C-1. 

Figure C-2. 

Figure C-3. 

Table 1. 

FIGURES 

Regional map of Alaska North Slope oilfields, 2004 ................................... 2 

Pipeline-height categories used for crossings by caribou in relation to availability along 

the Endicott pipeline/road corridor, northern Alaska. . ................................. 9 

Elevated pipeline design using "potato-masher" style of oscillation dampener, or TVA, for 

the Meltwater Project, northern Alaska ............................................. 30 

Pipeline elevated to 1.5-m minimum height and showing older spherical style and newer 

"potato-masher" style of oscillation dampeners, and reflectivity of standard sheathing, 

Kuparuk DS-2L project, northern Alaska ........................................... 31 

Pipelines with nonreflective sheathing and elevated to a minimum height of 2.1 m, 

constructed in winter 2001-2002, Kuparuk DS-3S project, northern Alaska ................ 32 

TABLES 

Study design criteria used to evaluate crossing success of caribou groups encountering 

pipeline/road corridors in the Prudhoe Bay and Kuparuk oilfields, northern Alaska ........... 4 

APPENDICES 

Appendix A. Measurement Units and Acronyms ................................................ 25 

Appendix B. Experts Consulted ............................................................. 27 

Appendix C. Infrastructure in Alaska North Slope Oilfields ....................................... 29 

Appendix D. Annotated Bibliography. . ...................................................... 33 

ii 
INTRODUCTION 

In the North Slope oilfields of arctic Alaska (Figure 

1 ), the oil carried in pipelines must remain hot to flow 

properly, both in gathering lines within the oilfields 

and for transport south through the Trans-Alaska Pipeline System (TAPS). From a practical standpoint, it is 

impossible to bury hot pipelines in ground containing 

pennafrost because thermal erosion of the ground ice 

(thermokarst) would soon compromise the stability 

of the ground and thus of the pipelines. Therefore, 

pipelines in arctic Alaska typically are insulated and 

elevated above the surface of the ground on structures 

consisting of horizontal cross members between metal 

pilings called vertical support members (VSMs). The 

most comprehensive compilation of North Slope infrastructure to date listed 724 km ( 450 mi) of pipeline 

corridors in the North Slope oilfields as of2001 (NRC 

2003: Appendix E), in addition to the 676 km (420 mi, 

or 53% of the length) of elevated pipeline along the 

1,287-km (800 mi) length of TAPS (BLM 2002). 

The potential effects of pipelines on the movements 

of caribou (Rangffer tarandus) in Alaska have been 

debated since planning began for the development of 

the North Slope oilfields and TAPS in the late 1960s. 

The effect of pipeline height on the ability of caribou 

to cross beneath elevated pipelines was addressed in 

applied research and impact overviews in the 1970s 

and l 980s (Child 1973; Cameron and Whitten 1976, 

1977, 1978; Klein 1980; Banfield et al. 1981; Eide et 

al. 1986; Curatolo and Murphy 1986; Shideler 1986; 

Carruthers and Jakimchuk 1987). Most of the information available up to the early 1990s was summarized in a 

review of mitigation-related research ( Cronin et al. 1994) 

prepared for the Alaska Caribou Steering Committee, a 

group comprising representatives from the Alaska Oil 

and Gas Association (AOGA), the Alaska Department 

of Fish and Game (ADFG), the U.S. Fish and Wildlife 

Service, and the North Slope Borough. 

By the late 1990s, oil development spread farther 

westward from the Kuparuk Oilfield to the Alpine Project on the Colville River delta and eastward from the 

Prudhoe Bay Oilfield to the Badami Project (Figure 1 ). 

The expansion of oil development into areas west of 

the Kuparuk field again raised the issue of pipeline 

height to prominence, this time for the local residents of 

Nuiqsut, the Ifiupiaq village located nearest to the oilfields (PAI 2001). Public involvement during the North 

Slope Borough permitting process for construction of 

Kuparuk Drill Sites 2-P (the "Meltwater" project) and 

3-S (the "Palm" project) underscored the concern of 

local residents about the adequacy of minimum pipeline 

height stipulations, especially for caribou encountering 

infrastructure during the winter, when snow accumulates 

on the ground beneath elevated pipelines, and for local 

residents traveling by snowmobile. This discussion continues today as oil development expands further from 

the Alpine project to associated "satellite" developments on the Colville delta and into the Northeast Planning Area of the National Petroleum Reserve-Alaska 

(NPR-A) (BLM 2004). 

The stipulations placed on development of oil and 

gas leases in the Final Integrated Activity Plan/Environmental Impact Statement (IAP/EIS) for the Northeast 

Planning Area of NPR-A (BLM 1998) specified that 

all pipelines would be elevated to a minimum height 

of 152 cm (5 ft; referred to hereafter as 1.5 m) above 

the ground surface. More recently, the Record of Decision (ROD) fortheAlpine Satellites Development Plan 

(ASDP) and the Final Amended IAP/EIS for the Northeast Planning Area ofNPR-A (BLM 2005) mandated 

that above-ground pipelines be elevated to a minimum 

height of 213 cm (7 ft; referred to hereafter as 2.1 m) 

above ground level, similar to the design used for the 

Kuparuk DS-2P and DS-3S project pipelines in 2001 

and 2002 (see Appendix C, Figure C-1). 

This review was undertaken to revisit the issue of 

pipeline height in relation to caribou crossing success 

and to assess the applicability of existing information 

to current questions. Specifically, how much clearance 

is needed to allow caribou to cross beneath elevated 

pipelines and how does height influence crossing success? Is 1.5 m of clearance adequate to allow caribou 

passage throughout the year? The answers to these 

questions can largely be extracted from a variety of 

studies conducted over the last three decades. This 

review focuses specifically on the issue of pipeline 

height in relation to crossing success, rather than on a 

broader evaluation of the response of caribou to linear 

developments, which would encompass a much larger 

body of literature and was beyond the scope of this 

review. For more information on the latter question, the 

reader is referred to other reviews and papers (Shank 

1979, Jakimchuk 1980, Smith and Cameron 1985a, 

Curatolo and Murphy 1986, Shideler 1986, Murphy and 

Curatolo 1987, WMI 1991, Cronin et al. 1994, Jalkotzy 

et al. 1997, Murphy and Lawhead 2000, Wolfe et al. 

2000, NRC 2003), most of which are included in the 

annotations prepared for this report. Our review focuses 

primarily on Alaska, where the bulk of the available 

information has been gathered, but information from 

other countries is included where pertinent. 
METHODS 

Previous reviews of mitigation-related research 

(Shideler 1986, Cronin et al. 1994) were used as primary 

resources to identify pertinent references, in addition 

to a search of ABR's database of caribou literature. 

An electronic search for published journal articles was 

conducted usingABR 's literature database from Current 

Contents® for Windows/Macintosh (Thomson Scientific, Philadelphia, PA). We included documents that 

have been published in the open scientific literature, as 

well as unpublished literature such as research reports 

by agency biologists and environmental consultants. 

Although the unpublished literature has not undergone 

the full peer-review process of journal publication (and 

hence is annotated with "no" under the peer-review 

field in the bibliographic database), it remains the only 

source of information on certain subjects. Most of the 

unpublished reports we used are known or presumed to 

have received some level of internal review by editors 

and some received outside review by agency biologists 

orotherresearchers.Mostofthereferenceswereviewed 

were on file in the ABR library in Fairbanks, and other 

references were obtained from libraries at the University of Alaska Fairbanks, through interlibrary loan, or 

through direct contact with other researchers. 

Selected references judged to be most relevant to the 

topic were annotated and submitted to BLM as a searchable database using ProCite® bibliographic software 

(version 5.0.3; Thomson ResearchSoft, Berkeley, CA), 

and the database contents are appended to this report 

(Appendix D). The measurement units used in text are 

metric (with English equivalents at first use), but the 

literature annotations list units as reported in the original 

publication; unit conversions are provided, along with 

acronyms used in text, in Appendix A. 

Selected experts in Alaska, Canada, Scandinavia, and 

Russia were contacted by telephone or e-mail to ask 

whether they were aware of any data collected since the 

review by Cronin et al. (1994) or older data that may 

never have been analyzed or reported. These contacts 

are listed at the end of the report (Appendix B). 

Data from studies conducted by ABR researchers 

in the Kuparuk Oilfield (summarized in Curatolo and 

Murphy 1986) and along the Endicott pipeline/road 

corridor (Lawhead et al. 1993a) were reviewed to assess 

whether reanalysis was warranted and feasible. Retrieval 

and reanalysis of the Kuparuk data sets were beyond 

the scope of this review. We reanalyzed the Endicott 

pipe-height selection data using the full data set, which 

was not available to Cronin et al. ( 1994) when their review was prepared. Pipeline heights crossed by caribou 

were compared with pipeline heights available in the 

Endicott study plots using chi-square goodness-of-fit 

tests; each pipeline interval between adjacent VS Ms was 

assigned to a height category based on field measurements (Lawhead et al. 1993a). We grouped crossings 

into the same 5 height categories used by Cronin et al. 

(1994)(<100, 100-149, 150-199,200-249,and>249 

cm, derived by combining several categories from the 7 

original 50-cm categories [Lawhead et al. 1993a]) and 

compared use to availability for all 3 Endicott study 

plots over all 4 years combined (1987-1990), for each 

of the study plots for all years combined, and for each 

year for all study plots combined. Each distance category was tested for significance using Bonferroni multiple-comparison tests (Neu et al. 1974, Byers et al. 

1984). Following Cronin et al. (1994), we also compared use to availability for pipeline heights <150 cm 

and 2':150 cm, as well as between the 150-199 cm and 

2:200 cm height categories. 

REVIEW AND SYNTHESIS 

Analysis of Crossing Success 

A note about terminology is useful to bear in mind 

when reading the literature on caribou passage across 

linear corridors. The concept of maintaining "free passage" by caribou across pipeline/road corridors was used 

widely in impact analysis and mitigation discussions 

in Alaska in the 1970s and 1980s but was not defined 

in quantitative terms; the concerns were that caribou 

movements should not be impaired to a degree at which 

harmful effects would occur and that areas of important 

habitat should not become unavailable. In discussing 

caribou crossings, it is useful to distinguish between 

a "barrier" effect (implying blockage or prevention 

of crossings) and an impediment, variously referred 

to as "obstruction" (Banfield et al. 1981) or a "filter" 

( Jalkotzy et al. 1997). The latter terms connote permeability rather than complete blockage, and thus are more 

applicable to caribou movements across linear corridors. 

The only examples of complete barriers are physically 

impassable structures such as large-diameter pipelines 

on or near the ground. 

The central difficulty in evaluating crossing success is 

that the investigator is faced with the problem of determining the "intent" of caribou to cross a linear structure. 

This evaluation has either compared the frequency of 

border crossings in treatment plots with those in control 

(reference) plots, or else has assumed that all animals 

that pass a certain point or approach within a certain 

distance of a structure "intend" to cross it. The criteria 

for defining crossing success have differed somewhat 

3 
among various studies, in terms of three criteria: approach distance for inclusion in the sample, percentage 

of caribou crossing, and variable duration of observations (Table 1 ). When caribou groups are deflected and 

move parallel to pipelines, they typically do so within 

50-250 m (Child 1973, Child and Lent 1973, Johnson 

and Lawhead 1989), but may subsequently move away 

farther if they are unsuccessful (Smith and Cameron 

1985b ). These observations indicate that an approach 

zone of at least 400 or 500 m should be adequate to 

evaluate caribou crossing success. 

Analysis of crossing success must account for the fact 

that not all caribou cross completely through studyp lots, 

even in the absence of infrastructure. The best data on 

this topic come from studies that included control plots 

withoμt any infrastructure. Fancy (1983) found that 

9 .1 % of the animals in his control plot reversed direction 

or "detoured around" hypothetical structures (located 

along two of the four borders of his grids). Curatolo 

and Murphy (1986) found that 34% of the groups in 

their control plots did not cross the northern borders 

(representing hypothetical structures), and they used 

that percentage to estimate the expected number of 

crossings in their treatment plots. Evaluation of crossing 

success is complicated by the difficulty in anticipating where (or why) movements wi11 occur and thus in 

obtaining adequate sample sizes for statistical analysis, 

especially when attempting to partition samples according to group type (sex/age composition), group size, and 

insect conditions. Hence, multiple years of study usually 

are required to produce adequate sample sizes. 

Analyses of pipeline crossings by caribou tend to be 

of two types. The most useful studies compared pipeline heights available in study areas with pipe heights 

actually used for crossings, using either chi-square tests 

or nonparametric Mann-Whitney tests. These studies 

were limited by the range of pipeline heights available 

and the effect of natural topographic features. Most 

studies compared crossing success of caribou groups 

under different conditions (e.g., presence of a road, 

insect presence, group size, direction of travel) but seldom used pipeline height as a variable directly. Those 

studies provided useful infonnation on the range of 

pipeline heights caribou crossed, but seldom provided 

strong evidence ofactual selection for specific pipeline 

heights. All investigators faced the difficulty of deciding 

what was available to caribou in their study areas, but 

no universal method was used to address this difficulty. 

The literature on caribou crossings of elevated pipelines is predominantly based on observational studies 

of caribou crossing under existing pipelines; only a few 

involved experimental studies of simulated pipelines. 

Because experimental studies were primarily conducted 

on low-elevation simulated pipelines with caribou or 

Table 1. Study design criteria used to evaluate crossing success of caribou groups encountering pipeline/road 

corridors in the Prudhoe Bay and Kuparuk oilfields, northern Alaska. 

Smith and Cameron 198:ia; 

Smith et al. 1994 

Coltrane &Lanctot 2000 · 

" Basis for calculating percentage crossing. 

Duration of 

Focal group could not be followed farther 

Group exited pl;t, or grnup 

crossed or retreatetl fn:ii11 mad · 

b Percentage of group crossing to be considered successful; actual percentage of total caribou individuals crossing usually was 

reported also. 

c Depended on plot dimensions. 

d Crossing success was calculated only for groups in ,vhich at least 1 caribou crossed. 

4 
reindeer, they did not directly address the minimum 

height needed for caribou to cross consistently under a 

pipeline. Observational studies of caribou and pipelines 

have several limitations. The pipeline height is often 

correlated with topographic features; river beds tend 

to have high pipeline heights while ridge tops tend to 

have lower pipeline heights. Therefore, it is difficult to 

differentiate between the effects of pipeline height and 

the influence of existing natural movement corridors. 

In addition, most areas have a limited range of pipeline 

heights available; most observational studies on the 

North Slope of Alaska were conducted in areas with a 

minimum pipeline height of 1.5 m (5 ft). 

Study plot sizes differed among studies, ranging from 

as small as 0.3 km2 to as large as 9 km2; most were in 

the l-3-km2 range (Table 1). Fancy (1983), Murphy 

(1984), and Murphy and Curatolo (1984) used two 

observers in different locations to cover their plots 

adequately, whereas the other studies used a single observer for each plot. Larger study plots are more likely 

to- be entered by caribou and crossings are more likely 

to be recorded in large plots, but the selection of plot 

size must balance the need to obtain adequate sample 

sizes with the need to see all parts of the plot well with 

the personnel available and to coordinat~ observations 

and data collection among multiple observers. 

An alternative approach to measuring crossing success 

used road surveys that did not rely on study plots but 

instead covered specific stretches of road repeatedly, 

up to several times a day (Smith and Cameron 1985a, 

Lawhead et aL 1993a, Smith et al. 1994). Lawhead et al. 

(1993a) collected data using both plot and road methods 

and found that crossing success calculated from road 

surveys tended to be higher than from study plots, as 

would be expected when groups could be followed for 

longer distances outside plot borders, but the differences 

were not significant. Biased results could result from 

road surveys, however, if the observer departed before 

crossing events ended (Smith and Cameron 1985a, 

Lawhead et al. 1993a). 

Some researchers have disagreed about the use of 

groups versus individual caribou as sample units for 

statistical analyses (Whitten and Cameron 1986). 

Although using groups as a sample unit has the disadvantage of weighting small groups and large -groups 

equally, it is clearly inappropriate to treat the individ~ 

uals composing a group as independent data points 

in a chi-square test or other simple statistical test. 

Lawhead etal. ( 1993a: Figure 3 .. 7) found strong cohesion 

among groups; that is, all or nearly all group members 

either crossed or failed in most crossing attempts. The 

presentation of percentages based both on groups and 

on the number of caribou in those groups was more 

useful in examining crossing success than was using 

either measure alone. Percentages based on numbers 

of individual caribou within groups provide useful information when presented as descriptive statistics, but 

use/availability analysis of crossing locations should be 

conducted using groups to avoid problems caused by 

lack of independence among group members. 

Pipeline Height 

Because the height of elevated pipeline is the central 

focus of this review, we describe here the major findings 

concerning caribou responses and crossing success for 

pipelines below and above the minimum height of 1.5 

m stipulated by the State of Alaska for above-ground 

pipelines in caribou range. It is important to understand 

that this height stipulation results in average heights 

that exceed 1.5 m. For instance, the average heights of 

pipeline in three plots studied by Curatolo and Murphy 

(1986: Table 3) were 182, 186, and 261 cm, and the 

overall range among all three plots was 119-432 cm 

(pipe below 1.5 m occurred in short sectionsimmediately adjacent to crossing ramps, which are short buried 

sections of pipe). 

The reports and studies that address this topic can be 

divided roughly into three categories: (1) studies that 

· specifically evaluated pipeline height at locations (VSM 

intervals) crossed by caribou in relation to availability; 

(2) studies of crossing success that did not evaluate 

pipeline height hut that occurred in areas where the 

.minimum design height of 1.5 m applied; and (3) reviews that discuss pipeline height as a factor affecting 

crossing success but draw on the information presented 

in the first two categories above ( e.g., Thompson et al. 

1978, Shideler 1986, Cronin et al. 1994, Jalkotzy et 

al. 1997, Wolfe et al. 2000). The first category is not a 

large body of work, comprising only studies conducted 

in the Kuparuk and Endicott development areas on the 

treeless North Slope and along TAPS, mainly in the 

forested Nelchina Basin of southcentral Alaska. The 

seco.nd category is a larger body of work but the effect 

of pipeline height is more difficult to ascertain, and the 

third category provides useful summaries but no new 

data on the topic of interest here. 

The responses of woodland caribou (both the boreal 

and mountain ecotypes) to linear features (roads, seismic lines, and pipeline corridors) have been evaluated 

in Alberta since the early 1990s and have produced 

substantial data, mostly from GPS telemetry and GIS 

spatial analyses. Woodland caribou in Alberta avoided 

roads, seismic lines, and streams at distances of up to 

250-500 m (Dyer 1999, Oberg 2001 ), but roads were not 

5 
a barrier to movement unless traffic was present (Dyer 

et al. 2002). Caribou were located farther than random 

from linear corridors but caribou mortalities attributed 

to wolves were closer to linear corridors, suggesting 

that the predation risk was higher along linear corridors 

(James and Stuart-Smith 2000). Because linear features 

in Alberta are largely cut through boreal forest, however, the results may not apply to barren-ground caribou 

in tundra landscapes. The findings from Alberta are not 

directly relevant to address the effects of pipeline height 

because of the lack of elevated pipelines and specific 

crossing studies. 

Our contacts with selected experts inAlaska, Canada, 

and Scandinavia (Appendix B) turned up no new (or 

unpublished older) sources of data on the effects of 

pipeline height on caribou crossing success. Most oil 

and gas pipelines in Alberta are buried (K. Smith, pers. 

comm.; D. Melton, pers. comm.) and few above-ground 

pipelines are present in the Northwest Territories, 

except for some short slurry pipelines at diamond mines 

that have not been studied (A. Gunn, pers. comm.). The 

recently released EIS for the Mackenzie Gas Project in 

northwestern Canada describes above-ground pipelines 

planned for development areas near the Mackenzie 

River delta, which are designed to be at least 1.5 m high, 

based on Alaska experience. Most of the pipelines associated with that large project will be buried, however. 

No new information specific to pipelines in Scandinavia 

was reported (C. Nellemann, pers. comm.; B. Forbes, 

pers. comm.). Despite continuing gas and oil development in Siberia (Forbes 1999), infonnation on the effects 

of above-ground pipelines is scant (B. Forbes, pers. 

comm.); our search for infonnation from Russia was 

hampered by the language barrier and lack of response 

from a Russian expert we attempted to contact. 

Pipeline Height Below 1.5 M 

Much of the emphasis in early work on the effects of 

above-ground pipelines focused on the potential barrier 

posed by low pipelines. A prominently cited example 

of a serious obstacle to the migration of a herd of wild 

reindeer from the Taimyr Peninsula in Siberia was the 

construction of two parallel gas pipelines, each 0.7 m 

in diameter, ~ 1-2 km apart, and 250 km long between 

the cities of Messoyakha and Norilsk, beginning in 

1968-1969 (Skrobov 1972; Hemming undated; Klein 

undated, 1980). Those pipelines were set on wooden 

supports with a ground clearance of 30-50 cm, and the 

tops of the pipelines were 1-1.5 m above the ground 

surface; as a result, they posed a barrier to reindeer except in certain locations. Fall migration and movements 

in early winter were heavily altered by the pipelines, but 

6 

some reindeer succeeded in crossing under the pipes in 

ravines where ground clearance was higher ( to ~ 2 m, 

which was judged to be a suitable minimum height by 

Russian biologists). Reindeer were able to cross later in 

the winter because of snow drifting over the pipelines. 

After the initial crossing difficulties were noted, short 

ramps were built over the pipelines and "portals" 

( stretches of pipe elevated to 3-6 m and 7 5-100 m wide, 

spaced at 30-40-km intervals) and lead fences were constructed to aid crossings. Despite these accommodations, 

only about a quarter of the herd succeeded in crossing 

the pipelines and lichen ranges near the pipelines were 

overgrazed and trampled. Ultimately, 54 km of lead 

fences were built to divert reindeer away from the pipelines into previously unoccupied mountain habitats. 

During planning for the TAPS project and Prudhoe 

Bay oilfield development in Alaska, several pipeline 

simulations were constructed in 1971-1972 to investigate the responses of caribou and reindeer and to 

evaluate the effectiveness of crossing structures (Child 

1973, 1974, 1975). Ground clearance was low (0.5 m 

and 0. 8 m, respectively) over most of the 3. I -km and 

2.4-km lengths of the two pipeline simulations in the 

Prudhoe Bay area, with several crossing ramps and 

special elevated sections ("underpasses" elevated 1.2, 

1.8, and 2.4 m high) placed along the pipelines. The 

principal finding was that most (77-85%) of the caribou 

that encountered those two low pipeline simulations 

detoured around orretreated from them, whereas 8-18% 

crossed over ramps and 5-7% crossed under the elevated sections (Child 1973). A few individuals (36, or 

0. 7%) actually crawled under the simulated pipelines 

at heights of 46-76 cm (Child 1973, 1974). 

Child and Lent (1973) studied the responses of 

reindeer in different seasons to another low pipeline 

simulation built across a small valley on the Seward 

Peninsula of western Alaska. The simulated pipeline 

had a ground clearance of ~0.6 m, a diameter of0.8 m, 

a length of 2.3 km, and included a ramp and a single 

section of higher pipe arcing from 0.6 m up to a maximum of~ 3. 8 m before descending to 1. 8 m. Reindeer 

were herded to the simulated pipeline to observe their 

responses and crossing attempts in several different 

trials, with mixed results. Most reindeer avoided the 

structure and paralleled it to the ends before crossing 

or else reversed course and left the area. Some crossed 

when snow drifts bridged the structure in late winter, 

and some crossings were reported during the insect 

season, although it was not known whether they used 

the ramp or crossed under the simulation. 

Reges and Curatolo ( 1985) constructed a small-diameter (20 cm), 2.3-km-long pipeline simulation in July 
1984 that was elevated to various heights during their 

study period (top and bottom at 108 and 88 cm, 77 and 

57 cm, 51 and 31 cm, and 36 and 16 cm in combination 

with 77 and 57 cm) in the Kuparuk River floodplain, 

a well-used travel corridor where caribou were likely 

to encounter the simulation. Crossing frequencies were 

significantly lower than expected at all heights, although 

some caribou crossed over the pipeline at all heights. 

Six (0.5%) of 1,254 caribou encountering the 108-cm 

height jumped over but that height was an effective 

barrier to crossings. The percentage crossing generally 

increased at the lower heights, and the lower height (36 

cm at the top) in the combined-height trial was crossed 

significantly more than expected. Caribou appeared to 

notice the simulation when ~ 100 m away, and most of 

the caribou approaching the simulation moved parallel 

to it within 20 m and detoured around the ends. 

A few other reports of caribou crossing under low 

pipelines were found in the literature in addition to 

the account by Child ( 1973). Adult bulls harassed by 

oestrid flies were observed crossing or standing under 

the TAPS pipeline in 1975-1976 at heights as low as 

1.1 m (Roby 1978) and 31 (4%) of711 caribou crossings under the Endicott pipeline during 1987-1990 

occurred at heights below 1 m (Lawhead et al. 1993a); 

three of those crossings were made under pipe <0. 5 m 

high by fly-harassed yearlings. Pipeline <1 m high was 

crossed significantly less than was available (Lawhead et 

al. 1993a). Caribou during spring migration in northern 

Canada were observed to jump over pole fences as high 

as 1. 8-2 m (Miller et al. 1972) and to detour around other 

fences (Mccourt et al. 1974, cited in Jakimchuk 1980). 

Pipelines elevated 0 .4-1.1 m above ground level in the 

older portions of the Prudhoe Bay field posed barriers to 

caribou crossings (Smith and Cameron 1985a, Shideler 

1986) in the absence of crossing ramps (whether by 

design or at roadways under which pipe was buried). 

Most of the pipelines in the Prudhoe Bay field were 

constructed in the 1970s before the 1.5-m minimum 

height was stipulated. Pollard et al. ( 1992) gave an 

account of a large-scale movement of ~4,000 Central 

Arctic Herd (CAH) caribou through the Prudhoe Bay 

field from the northwest to the south on 16 July 1991, 

requiring crossings of multiple corridors, which included 

several newer pipelines> 1.5 m high in addition to older 

pipelines elevated~ 1 m or less. The low pipelines were 

crossed using ramps (up to 95% of the 3,000-3,500 

caribou observed crossing used one ramp) and a few 

crossings also occurred where pjpelines crossed a stream 

drainage at heights above 1 m. 

Despite unusual occurrences of caribou crawling 

under or jumping over low structures, the evidence 

demonstrates overwhelmingly that caribou crossing 

success is blocked or significantly reduced when the 

clearance beneath elevated pipelines is 1 m or less. The 

information available on the effects of simulated and 

actual pipelines located on or near the ground leaves 

little doubt that low-elevation pipelines pose serious 

impediments or complete barriers to caribou movements; therefore, they should not be considered for use 

in caribou range. 

Pipelines Elevated 1.5 M And Higher 

Ro by ( 197 8: Appendix G) recorded 41 crossings of the 

TAPS pipeline on the North Slope at heights up to 5.1 

min the first two years after it was built (1975-1976), 

but did not specifically analyze the effects of height. 

We calculated the mean pipe height for 32 crossings 

he described as 2.2 m, and the mean height for 5 other 

attempts that apparently failed was 1.2 m ( although pipe 

height data were lacking for other failed crossings); no 

data on the availability of various pipe heights were 

included, however. Most of the crossings he described 

occurred in winter, but no data on snow depth were 

presented. Roby described several repeated attempts 

at crossings where the pipe was higher at the crossing 

than at the first approach. He noted that bulls seemed to 

accommodate to the pipeline and nearby vehicle activity 

in summer when harassed by oestrid flies. Most of the 

crossings involved milling, deflections, and repeated 

attempts on the approach side of the pipeline. The crossing attempts described by Cameron and Whitten ( 1976, 

1977) are the same as were reported by Roby, and a few 

more anecdotal accounts were listed by Cameron and 

Whitten ( 1978). 

Fancy (1983) presented results on crossing success 

from his second season of study at Pmdhoe Bay Drill 

Sites 16 and 17 on the floodplain of the Sagavanirktok 

River delta (Fancy 1982), but did not include data from 

the first year (Fancy et al. 1981 ), presumably because 

no pipelines were in place then. Fancy included no data 

on pipe height in his paper other than to note that state 

regulations dictated a minimum height of 1.5 m, and 

the roads and pipelines in his study area were '"each 

elevated approximately 2 m" (Fancy 1983: 193). He 

defined a crossing as successful if caribou crossed the 

first structure they encountered ( either pipeline or access 

road) and reported an overall success rate of 70. 7%, 

but did not differentiate between the two structures. 

Hence, his definition of crossing success did not permit analysis of the success of caribou in crossing the 

entire pipeline/road corridor, so definitive comparison 

with other studies is problematic (Smith and Cameron 

1985a). 

7 
The first detailed examinations of crossing success in 

the North Slope oilfields that included specific data on 

pipeline height were conducted along the newly constructed Kuparuk pipeline in 1981-1983 by Curatolo et 

al. (1982), Curatolo and Murphy (1983), and Curatolo 

(1984). The findings of those studies were published 

by Curatolo and Murphy ( 1986), along with additional 

data collected along gathering pipelines in the western 

Kuparuk oilfield by Murphy and Curatolo (1984) and 

Murphy ( 1984 ). Curatolo and Murphy ( 1986) reported 

that the mean height (301 cm) of pipe under which 

caribou crossed in one of their three plots in 1981, the 

first year the Kuparuk pipeline was in place, was significantly higher than the mean height (261 cm) of pipeline 

available in that plot. For five other combinations of 

plots and years, the mean height under which caribou 

crossed did not differ from the mean height available in 

the plots (which was 182 cm and 186 cm in their other 

two plots). They concluded that "pipe height was not 

an important factor in crossing site selection" within 

the range of pipe heights they studied (Curatolo and 

Murphy 1986: 222) and that topography may have 

influenced caribou to cross where the pipeline was 

higher. The pipeline plot where higher pipe was selected in 1981 included very high pipe (to 4.3 m) because 

it crossed the Kuparuk River floodplain, which was a 

well-used travel corridor by caribou. 

The caribou monitoring study for the Endicott Environmental Monitoring Program provided the second 

set of data that specifically analyzed caribou crossings 

in relation to pipeline height. The four years of that 

study ( 1987-1990, for which separate annual reports 

were prepared) were summarized in a final synthesis 

report by Lawhead et al. (1993a). They concluded that 

the use of 7 height categories (in 50-cm increments, 

range 38-335 cm) differed significantly from availability in all years over all plots combined and within 

two of three plots over all years; use did not differ from 

availability in the other plot. Pipeline heights below 1 

m ( on ridges, dunes, and next to crossing ramps) were 

crossed significantly less than expected. 

Using a draft data set (n = 661 crossings) obtained 

before the final synthesis (Lawhead et al. 1993a) was 

completed, Cronin et al. ( 1994) reanalyzed the Endicott 

pipe-height data set using 1.5 m as a threshold height 

and concluded that pipeline heights below 1.5 m were 

used significantly less than expected. They also concluded that pipeline elevated higher than 2 m was selected 

overpipe 1.5-2mhigh. We repeated theiranalysisusing 

the final Endicott data set (n = 711 crossings) divided 

into 5 height categories (Figure 2) instead of the original 

7 categories, and found a significant difference among 

8 

height categories for all plots and years combined 

(X2 = 29.9, df = 4, P < 0.001 ). The number of crossings 

in the < 100-cm category was lower than expected (P < 

0.01) and the number in the 15 0-199 cm category was 

higher than expected (P < 0.05). In no other category 

did the number of crossings differ significantly from 

expected values (P> 0.05). In plot 1, significantly fewer 

crossings occurred in the < 100-cm category (P <0.01) 

and more than expected occurred in the 200-249-cm 

category (P < 0.01); use of no other category was significantly different from expected (P > 0.05). There 

were no significant differences from expected values 

for any height category in plot 2 (P < 0.097). In plot 3, 

significantly fewer crossings occurred in the < 100-cm 

category (P <0.01) and more than expected occurred in 

the 150-199-cm category (P < 0.01 ); use of no other 

category was significantly different from expected 

(P > 0.05). There were significant differences in use 

among height categories in 198 7 (X2 = 13 .1, df = 4, P 

= 0.011) and 1988 (X2 = 21.3, df = 4, P < 0.001), but 

not in 1989 or 1990 (P > 0.05). In 1987 and 1988, the 

significant difference resulted from fewer-than-expected 

crossings in the <100-cm category (P < 0.01). In the 

overall combined sample, -the number of crossings differed significantly between pipe heights < 150 cm and 

2:150 cm (X2 = 18.8, df = 1, P < 0.001), as Cronin et 

al. (l 994) reported. Contrary to their results, however, 

we found no significant difference in use between the 

150-199-cm and 2:200-cm categories (X2 = 0.05, df= 

1, P = 0.822), indicating no selection for pipe higher 

than 2 m during summer. 

Johnson and Lawhead (1989) used focal-group sampling to investigate the responses of caribou groups to 

Kuparnk oilfield infrastrncture in summer 1988. Although they did not collect pipe-height data, all of the 

pipelines in their study area were elevated at or above 

the required minimum height of 1.5 m. They reported 

high crossing success for the 198 corridor crossings 

they observed, based on both groups (82% overall for 

groups in which >50% of the members crossed) and 

total caribou (83% overall). Their definition of crossing 

success differed somewhat from other studies because 

they did not use study plots. Only groups that approached 

corridors closely (<100 m) were included, and success 

was calculated only for groups in which at least one 

caribou crossed; thus, the crossing success percentages 

they reported were primarily measures of group cohe-

. sion. Deflections also were recorded, however, and all 

groups that deflected eventually crossed. This study 

was the only one to examine crossing success in terms 

of the number of adjacent pipelines. No difference was 

found between corridors with 1-5 pipes and those with 
60% 

mAvailable (n=303) 

50% • Used by caribou (n= 711) 

40% 

-

C 

GI 

.. 

u 30% 

GI 

a. 

20% 

10% 

0% 

<100 100-149 150-199 20()-.249 >249 

Pipeline Height category (cm) 

Figure 2. Pipeline-height categories used for crossings by caribou in relation to availability. Data were combined 

for 3 study plots during 1987-1990 (Lawhead et al. 1993). 

6-10 pipes, but no successful crossings were recorded 

at corridors with 11-15 adjacent pipes ( a category 

that was restricted to a relatively small portion of the 

oilfield) except when oestrid flies were active, and the 

only attempted crossing of 16-19 adjacent pipelines 

was unsuccessful. Large numbers of adjacent pipelines 

tend to occur along busy stretches of road near major 

processing facilities, so traffic may exert an effect on 

crossing attempts in such locations. 

Along the roadless Badami pipeline corridor, Coltrane 

and Lanctot (2001) studied caribou crossing success to 

evaluate whether it differed between VSM intervals with 

and without pipeline oscillation dampeners that hung 

down 51-94 cm at two points within each interval, over 

21 % of the pipeline length. Although they did not evaluate the effect of pipeline height, all but ~ 182 m of that 

40-km pipeline was elevated to the required minimum 

height of 1.5 m. They reported that, although group success ( using the criterion of >50% of members crossing) 

did not differ significantly between sections with ( 3 7%) 

and without ( 58%) oscillation dampeners, fewer caribou 

individuals crossed intervals with dampeners (27%) than 

intervals without ( 63 % ) . The latter tests used individual 

animals as replicates, however, and they concluded that 

their study design was not conducive to drawing firm 

conclusions due to the difficulty of detennining "intent" 

to cross the pipeline and to the possible confounding 

effects of buried pipeline in riparian habitat near one 

of their plots and of traffic near the other plot. Use of 

video cameras did not allow quantification of crossing 

success, but similar numbers of caribou were recorded 

crossing under pipeline with dampeners (813 caribou) 

and without them (639 caribou). A follow-up study on 

the Badami pipeline (Noel et al. 2002) did not attempt 

to evaluate crossing success, but concluded that the 

mean numbers of caribou crossing under the elevated 

pipeline (3.8 caribou per day) did not differ from those 

crossing sections of pipeline that were buried in riparian 

habitats (5.4 caribou per day). 

In south-central Alaska, Eide et al. ( 1986) studied the 

movements of the Nelchina Caribou Herd in relation to · 

the TAPS pipeline during the first winter of operation 

( 1977-1978), and crossings of the TAPS pipeline by that 

herdduringspringandfallmigration in 1981-1983 were 

studied by Carruthers et al. ( 1984; results published as 

Carruthers and Jakimchuk 1987). Together with Cameron and Whitten (1976, 1977, 1978) and Roby ( 1978), 

those studies are the only sources of pipeline height 

data on caribou crossings outside of the postcalving and 

insect seasons. Eide et al. (l 986)reported that caribou 

selected against elevated pipeline heights below 2.1 m 

and tended to select those above 2.1 m. They speculated 

that pipeline crossings by caribou might be inhibited or 

blocked in a severe winter with deep snow. 

Carruthers and Jakimchuk ( 1987) reported that 93% 

of the length of above-ground pipeline in their study 

area was elevated to 1.8 m or higher. The mean height 

of pipeline crossed by caribou during migrations (2.5 

9 
m) was similar to the mean height available (2.3 m). 

Although this difference was statistically significant, 

the authors pointed out that there was little variation 

in height over long sections of the pipeline and most 

groups (92%) crossed the corridor at the first point of 

encounter, regardless of buried or above-ground pipeline mode or height, and thus showed little indication 

of height selection. Snow depth (<44-52 cm in spring 

and 25-33 cm in fall) was 32% lower on the TAPS 

right-of-way than in undisturbed habitat nearby and 

was not considered to be an important factor influencing crossing locations. Neither Eide et al. (1986) nor 

Carruthers and Jakimchuk (1987) found indications 

of diminished use of traditional migration routes after 

TAPS construction, and both found that a long buried 

section intentionally placed in a traditional spring 

migration route was used heavily. Shorter crossing 

structures ( shmi burials called '"sag bends" and short 

"designated big game crossings" elevated ~3 m) were 

used little and were not preferred by caribou. 

The presence of deep snow drifts adjacent to roads in 

the Kuparuk Oilfield eliminated the space for caribou 

to pass beneath pipelines in years of late snowmelt 

such as 1982 (Smith and Cameron 1985a) and 2001 

(B. Lawhead, personal observation), creating a potential barrier until the drifts melted. No studies have 

quantified the potential effects of snow drifting on 

caribou crossing success in the North Slope oilfields, 

in part because few CAH caribou winter that far out on 

the coastal plain. Nevertheless, the issue of adequate 

clearance under pipelines in winter emerged during the 

permitting process for the Kuparuk DS-2P (Meltwater) 

project in winter 2000-2001. 

As a result of that concern, Pullman and Lawhead 

(2002) measured snow depth under pipelines separated 

from roads and elevated at least 1.5 m in the western 

Kuparuk field and on the Colville River delta to examine the clearance between elevated pipelines and 

the snow surface. They found that landform, pipeline 

orientation with respect to prevailing winds, and pipe 

clearance could be used to predict where significant 

accumulations of snow might occur under pipelines. 

Most snow depth measurements (59% in March and 

5 5% in April 2001, a winter of slightly above average 

snowfall) did not differ from background levels located 

upwind. Snow depth was significantly greater than 

background levels at about a quarter of the sampling 

sites (24% in March and 27% in April), and was significantly less than background at 183⁄4 of the sites. Snow 

accumulation was greater in thaw basins and in some 

riverine habitats, under east-west-oriented pipelines 

as they converged on the prevailing wind direction, 

10 

and where clearance below pipelines was lower. The 

last point suggested a feedback mechanism: "Decreased 

clearance between an elevated pipeline and the ground 

enhances the windbreak effect of the pipeline" and 

greater accumulations were found where clearances 

already were reduced (Pullman and Lawhead 2002: 18). 

Plowing of an ice road immediately adjacent to one of 

the pipelines in that study caused increased snow depth 

under the pipe, which reduced clearance. 

In summary, the available data on pipe-height selection 

by caribou demonstrate that pipelines elevated to the 

minimum height of 1.5 mare adequate to accommodate 

crossings by caribou during snow-free periods ( Curatolo 

and Murphy 1986, Lawhead et al. 1993a, Cronin et al. 

1994). Although fewer data are available on crossings 

of elevated pipelines in winter, they indicate that pipeline heights in the range of 2.1-2.5 mare more likely 

to be used by caribou than lower heights (Cameron 

and Whitten 1976, 1977, 1978; Roby 1978; Eide et al. 

1986; Carruthers and Jakimchuk 1987). The responses 

of caribou to pipelines depend largely on other factors 

that influence crossing success, however, as described 

in the next section. 

Other Factors Affecting Crossing Success 

All investigations of caribou crossing success are 

faced with the difficulty of isolating the contribution 

of individual factors in highly complex situations that 

often defy statistical analysis. The following sections 

briefly review other, potentially confounding factors 

that have been evaluated in studies of crossing success, recognizing that attempts to isolate the effects 

of specific factors risk oversimplifying the complex 

nature of caribou responses to pipeline/road corridors. 

More discussion of most of these factors is available in 

other reviews and papers, such as Smith and Cameron 

( 1985a), Curatolo and Murphy (1986), Shideler (1986), 

Lawhead et al. (1993a), and Cronin et al. (1994). 

Infrastructure Design 

The design and layout of infrastructure ( see Appendix 

C for descriptions of North Slope infrastructure) affect 

the responses of caribou to oilfields. One of the most 

important design elements is the distance to and traffic 

levels on roads adjacent to elevated pipelines. Studies of 

crossing success in the Kuparuk Oilfield (summarized 

by Curatolo and Murphy 1986 and Cronin et al. 1994) 

quickly demonstrated the effect of road proximity and 

traffic levels on crossing success ( described separately 

below under Traffic). Most pipelines in the portions of 

the North Slope oilfields built in the 1970s and 1980s 

are within 20-30mofroads. Curatolo and Reges (1986) 
found that crossing success was significantly lower than 

expected at separation distances <91 m (300 ft) and 

recommended that the minimum separation distance 

should be 122 m (400 ft). That recommendation was 

expanded to 152 m (500 ft) by Cronin et al. (1994). 

Consequently, the basic design of pipeline/road corridors was changed to separate pipelines from roads at 

distances consistent with these recommendations. For 

example, the mean separation distance between the access road and pipeline rack for the recently constructed 

Kuparuk DS-2P (Meltwater) project is 188 m (range 

157-257 m; Lawhead et al. 2004). In the 1980s, the 

North Slope Borough specified that the maximum separation distance between pipelines and roads should be 

no more than 305 m (1,000 ft), primarily out of concern 

for leak detection. With the advent of more sophisticated 

leak detection methods such as monitoring from aircraft 

equipped with thermal imaging (Forward-Looking 

Infrared, or FLIR) equipment, newer pipelines (most 

notably the Alpine and Badami pipelines) have been 

constructed without any gravel roads nearby. 

Pipelines in the North Slope oilfields typically are 

placed on the upslope sides of roads to enhance spill 

containment in the event of pipeline leaks. For east-westoriented roads, this practice usually means that pipelines 

are located on the southern sides of road corridors and 

thus are the first structures encountered by mosquitoharassed caribou moving north to coastal relief habitat. 

The order of encounter is reversed for caribou moving 

inland to foraging areas. Although most of the crossing studies we reviewed examined crossing success 

by caribou moving inland after insect harassment subsided, none attempted to evaluate the effect of pipeline 

placement in relation to roads. The net effect of encountering pipelines first can be hesitation, delays, and 

potential deflections of insect-harassed caribou where 

pipelines at least 1. 5 m high are located within 100 m of 

roads with moderate to high levels of traffic (Curatolo 

and Reges 1986, Johnson and Lawhead 1989). Caribou 

encountering the pipelines often hesitate and then are 

disturbed and crossings interrupted by approaching traffic, as described by Curatolo and Murphy (1986). 

The location and directional orientation of pipeline/ 

road corridors in relation to caribou movement patterns 

also can affect crossing success. Infrastructure located 

at or near the Beaufort Sea coast is in a zone that is the 

destination formosquito.;harassed caribou, meaning that 

caribou may not need to cross to achieve relief from 

harassment. The Oliktok Point and Milne Point roads 

make similar transitions from inland areas to coastal 

insect-reliefhabitat, and large numbers of CAH caribou 

usually cross annually during large-scale movements 

in the insect season (Johnson and Lawhead 1989). 

The orientation of the Endicott pipeline/road corridor 

changes from east-west (generally perpendicular to 

most caribou movements) on the inland portion of the 

corridor to northeast-southwest ( more parallel to movements) along the outer portion near the coast. Lawhead 

et al. (1993a) noted that insect-harassed caribou that 

encountered the corridor at shallow angles of movement 

in the outer portion appeared to deflect and did not need 

to cross the corridor to reach relief habitat. Jakimchuk 

( 1980) noted a tendency for migrating caribou in northern 

Canada to deflect onto seismic lines after shallow-angle 

approaches, which is consistent with the tendency of 

caribou to seek the path of"leasttopographic resistance" 

(LeResche and Linderman 1975) or ''least energetic 

resistance" (Bergerud et al. 1984). 

Crossing Ramps 

Observations of caribou responses to simulated pipelines (Child 1973), the TAPS pipeline (Cameron and 

Whitten 1976, 1977, 1978), and pipelines in the Kuparuk field (Curatolo et al. 1982; Curatolo and Murphy 

1983, 1986; Smith and Cameron 1985a, 1985b) led to 

requirements in the late 1970s and 1980s that crossing 

ramps be built over pipelines as mitigative measures to 

accommodate caribou crossings. Research focused on 

the effectiveness of ramps in the Kuparuk field (Murphy 

1984, Murphy and Curatolo 1984, Curatolo and Reges 

1986) and the Endicott pipeline/road corridor (Lawhead 

et al. 1993a) 

Studies demonstrated that crossing ramps, including 

buried sections of pipe at road crossings, were preferred 

by caribou for pipeline/road crossings (Child 1973; 

Curatolo et al. 1982; Curatolo and Murphy 1983, 1986; 

Smith and Cameron 1985a, 1985b; Shideler 1986; 

Lawhead et al. 1993a; Cronin et al. 1994 ), and indeed 

appeared to be the only reasonable option for crossings 

in areas oflow pipelines in the Prudhoe Bay field (Pollard et al. 1992, Cronin et al. 1994 ). Although ramps 

tended to be preferred by caribou crossing pipelines, the 

results were equivocal as to whether they were necessary for caribou to cross pipelines elevated at least 1.5 

m above the ground. Curatolo and Reges ( 1986) found 

no difference in crossing success of the·Oliktok Point 

Road con-idor after they blocked ramps in their study 

plots. The amount of time spent in study plots did not 

differ between caribou groups that crossed ramps and 

those that crossed under elevated pipeline, indicating 

that ramps did not expedite crossings (Lawhead et al. 

1993a). The utility oframps in facilitating pipeline/road 

crossings by large groups was mixed, with some studies 

reporting crossings by large groups and hypothesizing 

11 
that they may promote crossings by large groups that 

otherwise were having difficulty (Curatolo and Murphy 

1986, Smith and Cameron 1985a, 1985b ). In contrast, 

Lawhead et al. (1993a) found that the mean size of 

groups crossing under elevated pipeline was larger than 

that for groups crossing ramps. 

Based on the results of applied research and changes 

in corridor design, ramps have not been used as mitigative measures in more recent developments, although 

they clearly are still necessary in the portions of the 

Prudhoe Bay field where pipelines are lower than 1.5 

m. Separation of pipelines from adjacent roads has 

been used as a mitigative measure instead of ramps in 

recent projects on the North Slope, resulting in more 

effective mitigation along much longer stretches of 

pipeline. Murphy and Lawhead (2000) suggested that 

ramps be considered where topography or infrastructure could funnel caribou movements into specific 

locations where crossings might be impeded, whereas 

Gilders and Cronin (2000) suggested that eliminating 

ramps was itself a mitigative measure to reduce direct 

impacts on wetlands and surface water flow caused by 

placement of gravel fill. 

Traffic 

Research in the North Slope oilfields has confirmed 

that the most important factor affecting caribou crossing 

success at pipeline/road corridors is traffic on nearby 

roads. Crossing success in study plots with pipelines 

alone (elevated to the minimum height of 1.5 m) did 

not differ significantly from that in control plots or with 

roads alone, but crossing success was significantly 

reduced in study plots containing an elevated pipeline 

next to a busy road. The combination ofhigh-traffic roads 

(15 or more vehicles/hr) adjacent to elevated pipelines 

created a synergistic effect that reduced caribou crossing success (Curatolo et al. 1982; Curatolo and Murphy 

1983, 1986; Murphy 1984; Murphy and Curatolo 1984, 

1987). Several early reports indicated that caribou apparently preferred to cross roads where berm height was 

lower(Hanson 1980, Cameron and Whitten 1976, 1977, 

1978). The similarity of 1.5-m height of road berms to 

the 1.5-m height of adjacent pipelines can create a visual 

obstruction, similar to concealing cover for predators. 

The potential for delays is high when roads are nearby 

because caribou hesitating at pipelines are more likely 

to be disturbed by approaching vehicles and retreat from 

the pipeline (Curatolo and Murphy 1986). 

The level of traffic that results in reduced crossing 

success has been quantified in several studies. Curatolo 

and Murphy (1986) reported that crossing success was 

low at the Spine Road with an average rate of 15 ve12 

hicles/hr. Lawhead et al. (1993a) found that crossing 

success was significantly lower above a median rate of 

18.6 vehicles/hr in 1987, the year of, highest traffic in 

their Endicott study, and over all four years when the 

rate exceeded 15 vehicles/hr. Several other comparisons did not detect significant differences for the three 

other years when the median rate was lower, although 

a uniform trend for lower crossing success at higher 

traffic rates was evident. Traffic was a confounding variable in the anecdotal account by Smith and Cameron 

( 1985b ), who reported average rates of20-21 vehicles/ 

hr on the Spine Road when they observed two large 

groups having difficulty crossing the Kuparuk pipeline. 

Murphy and Curatolo (1984) reported significantly 

reduced crossing success where traffic averaged 32 

vehicles/hr. 

Crossing success of caribou encountering only roads 

or only pipelines did not differ from crossing frequencies in control plots without infrastructure in the Kuparuk 

studies summarized by Curatolo and Murphy ( 1986). 

Consequently, those authors recommended separating 

pipelines from adjacent roads to make the two types of 

structures easier to cross in separate encounters. Along 

the Oliktok Point Road, Curatolo and Reges ( 1986) 

found that crossing success was significantly lower 

where the separation distance between pipelines and 

the road was <91 m. In the Kuparuk oilfield, 91 % of 

the deflected crossings observed by Johnson and 

Lawhead ( 1989) occurred at corridors where the pipeline/road separation distance was < 100 m. 

Group Dynamics 

Group leadership has been recognized as an important 

factor maintaining group cohesion in caribou crossings 

of linear features (Miller et al. 1972), and successful 

crossings of pipeline/road corridors often were initiated 

by bolder individuals (Curatolo et al. 1982). The frequency of instantaneous behavioral reactions of caribou 

to human-related stimuli increases greatly within 100 

m of disturbing stimuli (most of which were vehicles; 

Curatolo and Murphy 1986, Johnson and Lawhead 

1989, Lawhead et al. 1993a), so the frequency ofreactions increases substantially during crossing attempts. 

Child ( 1 973) noted that the responses of groups tended 

to be influenced by the most reactive individual, and 

Curatolo et al. (1982) noted that yearlings often balked 

at crossing under the Kuparuk pipeline. In one instance, 

fewer than 5 reactive individuals appeared to precipitate 

the failure of 107 bulls to cross the Oliktok Point Road 

corridor on 8 July 1992, the only ones that failed to 

cross out of an aggregation of ~6,000 caribou (Lawhead 

and Flint 1993). 
A tendency approaching an all-or-none response 

was noted in crossing success along the Endicott pipeline/road con-idor (Lawhead et al. 1993a: Figure 3-7); 

all group members crossed in 41--43% of the groups 

included in their plot and road samples and no group 

members crossed in 41-42% of the remaining groups 

in the same samples. This tendency suggests that the 

definition of crossing success based on >50% of the 

individuals in a group crossing is reasonable. High levels of crossing success can result if a cohesive pattern 

of crossing becomes established and is not interrupted 

by traffic (Johnson and Lawhead 1989, Lawhead et al. 

1993a). 

Large groups of caribou (usually defined as > 100 

individuals) have been noted to have difficulty crossing pipeline/road coITidors (Child 1973; Smith and 

Cameron 1985a, 1985b; Curatolo and Murphy 1986; 

Shideler 1986), but firm conclusions arc difficult to 

draw because results varied among studies and were 

confounded by insect conditions and traffic (Child 1973, 

Curatolo and Murphy 1986, Lawhead ct al. 1993a, 

Cronin ct al. 1994 ). Caribou respond to mosquito harassment by forming large groups (White et al. 1975, 

Roby 1978, Lawhead 1988), which usually take longer 

to cross pipeline/road corridors, thereby increasing the 

probability of disturbance by traffic or other stimuli 

that may intenupt or interfere with pipeline crossings 

(Curatolo and Murphy 1986). Although large groups 

tended to be less successful than smaller ones in the 

early Kuparuk pipeline studies, the difference 'Was not 

significant (Curatolo and Murphy 1986 ). Crossing success among three group-size categories was variable 

over all years and insect conditions in the Endicott 

studies, but the crossing success of groups of l 00 or 

more caribou did not differ significantly from groups 

of 2-10 or 11-99 caribou (Lawhead et al. 1993a). Part 

of the difficulty in interpreting results among studies 

is that large groups occurred less frequently, so sample 

sizes tended to be small and not always conducive to 

statistical analysis. 

Catibou segregate into bull-dominated and cow-dominated groups throughout most of the year, but mixed 

groups form during the insect season and rut (breeding season) (Roby 1978). Cows with young calves are 

widely recognized as being sensitive to human disturbance, but Child ( 1973) noted that cow groups crossed 

simulated pipelines more readily than did bull groups 

during the insect season. On the other hand, bulls were 

regarded as being more tolerant of human disturbance 

during TAPS construction (Roby 1978; Cameron and 

Whitten 1976, 1977, 1978). All sexes and ages have been 

recorded crossing under pipelines that meet the 1.5-m 

minimum height requirement, with no consistent trend 

in crossing success by sex and age across all studies. 

Curatolo and Murphy ( 1986) and Cronin ct al. ( 1994) 

reported no difference in crossing success among different group types. Group type docs not appear to be an 

important variable affecting pipeline-crossing success 

<luring the insect season, when group dynamics are 

highly variable over short time spans. 

Insect Harassment 

Harassment by mosquitoes (Aedes spp.) and parasitic 

flies of the family Oestridac-warblc flies (Hypodernw 

tarandi) and nose-bot flies ( Cephenemyia trompe), 

together known as oestrid flies-exert profound influences on caribou behavior and movements on the Arctic Coastal Plain of Alaska during the summer insect 

season (White ct al. 1975, Roby 1978, Shideler 1986, 

Murphy and Lawhead 2000). Mosquitoes emerge by 

late June and harass caribou on warm, calm days until 

late July, whereas oestrid flies emerge later in early to 

mid-July and harass caribou into mid-August. Caribou 

aggregate into large groups and move to the sea coast 

in response to mosquito harassment, but groups break 

up and disperse in response to fly harassment (White 

et al. 1975, Roby l 978, Lawhead 1988). 

There is a qualitative difference in the response of 

caribou to infrastructure during the insect season. Caribou harassed by mosquitoes move rapidly and appear to 

be highly motivated to cross pipeline/road corridors, but 

crossing success can be highly variable, depending on 

traffic and other disturbing stimuli (Child 1973, Johnson 

and Lawhead 1989, Lawhead ct al. 1993a, Cronin ct 

al. 1994). Caribou moving inland again after harassment subsides generally exhibit high crossing success, 

although the rate of movement is slower in the absence 

of insect harassment, and crossing events can be more 

protracted (Murphy and Curatolo 1987, Johnson and 

Lawhead 1989, Lawhead et al. 1993a). 

The behavioral responses of caribou to infrastructure 

under oestricl fly harassment constitute a confounding 

factor in interpreting crossing success because gravel 

pads, buildings, and pipeline/road corridors often attract 

caribou seeking to avoid flies. Caribou often seek shade 

· under pipelines and may cross under them repeatedly 

in this season (Roby 1978, Curatolo and Murphy 1986, 

Johnson and Lawhead 1989, Pollard and Noel 1994, 

Lawhead et al. 1993a). Mosquito-harassed groups tend 

to detour around gravel pads and across roads, with a 

high incidence of deflections, whereas fly-harassed 

caribou often move onto gravel structures and have 

higher crossing success (Smith and Cameron 1985a, 

Curatolo and Murphy 1986, Johnson and Lawhead 

13 
1989, Smith et al. 1994). For instance, Lawhead et 

al. (1993b) reported that 4,600 caribou (~20% of the 

Central Arctic Herd at the time) congregated on three 

gravel pads in the western Kuparuk Oilfield on 14 July 

1993 when flies were active. Therefore, this attraction 

must be considered when considering the effects of 

pipelines on crossing success. 

Differing or conflicting responses of caribou to 

different insect pests help to explain some apparent 

contradictions in findings about crossing success. For 

example, Lawhead et al. (1993a) noted the anecdotal 

account of two large groups that had difficulty crossing 

the Kuparuk pipeline/road corridor (Smith and Cameron 1985b) also appears to have been confounded by 

the presence of oestrid flies as well as by traffic, judging from data on insect activity collected in the same 

area at the same time (Curatolo et al. 1982, Curatolo 

and Murphy 1983). Lawhead et al. (1993a) found that 

crossing success was significantly higher when caribou 

were harassed by mosquitoes alone (before the seasonal 

onset of widespread oestrid fly harassment) than when 

both mosquitoes and oestrid flies were active. Under 

those conditions, large groups that reached the pipeline/ 

road corridor often milled about and stood or walked 

on the road or under the pipeline as though responding 

primarily to flies, whereas those that crossed and moved 

away resumed a higher rate of movement directed 

toward the coast, as though responding primarily to 

mosquitoes. On the other hand, Johnson and Lawhead 

(1989) found that group cohesion during crossings 

was higher for groups under simultaneous harassment 

by mosquitoes and oestrid flies than it was when only 

mosquitoes were active. 

Season 

Nearly all of the studies described thus far regarding 

caribou crossing success in northern Alaska oilfields 

were conducted during snow-free periods, focusing on 

the summer insect season (late June to mid-August) 

because that is the period when caribou of the Central 

Arctic Herd repeatedly encounter infrastructure while 

moving to and from mosquito-relief habitat at or near 

the Beaufort Sea coast (Murphy and Lawhead 2000). 

Little effort was made to study crossing success before 

calving in spring (Cronin et al. 1994), when movement 

rates were low and few caribou were in the oilfield region, and maternal cows with newborn calves generally 

avoided roads (Dau and Cameron 1986, Lawhead 1988, 

Cameron et al. 1992), so little crossing information 

could be collected during that period. 

The studies conducted on the N elchina Herd in relation 

to TAPS (Eide et al. 1986, Carruthers and Jakimchuk 

14 

1987) provided the best information on crossings in 

relation to pipe height in winter. Along with the anecdotal observations in fall and winter along TAPS in 

northern Alaska (Cameron and Whitten 1976, 1977, 

1978; Roby 1978), those studies suggest that caribou 

prefer higher sections of pipeline when snow cover is 

present. Even where pipelines are elevated to a minimum of 1.5 m, such as in the Kuparuk field, drifting of 

snow under elevated pipelines near roads may create 

an obstruction that impairs crossings in "late" springs 

when snowmelt is delayed, such as in 1982 (Smith and 

Cameron 1985a) and 2001 (ABR, Inc., unpublished 

observations). Although Pullman and Lawhead (2002) 

did not collect data on caribou crossings, they found 

that the pipe-to-snow clearance beneath North Slope 

pipelines in late winter was reduced below 1.5 m along 

about a quarter of the length of pipeline stretches they 

sampled. They noted that clearance was more likely to 

be reduced under lower pipe and where snow-clearing 

on ice roads along pipelines created berms. That study 

also found that adequately separating pipelines from 

roads eliminated the drifting under pipelines that is 

commonly seen in older parts of the oilfields where 

pipelines are close to roads. 

Habitat And Topography 

The amount of experience that caribou have had 

with tall vegetation has been considered to affect their 

responses to pipelines (Klein 1980, Eide et al. 1986, 

Carruthers and Jakimchuk 1987). Klein (1980) thought 

that the visual effects of overhead structures such as 

elevated pipelines were greater in tundra than in forested 

landscapes, but also noted that responses were much 

stronger to human activity than to infrastructure. 

Although habitat influences have been mentioned 

as possible confounding factors in assessing crossing success under elevated pipelines, few attempts 

have been made to account for the potential effect of 

habitat, which poses difficult problems in study design. 

Curatolo et al. (1982) found that caribou tended to use 

higher-elevation pipe than was generally available in 

their study plot, but the high pipe was located on the 

floodplain of the Kuparnk River, which was a heavily 

used travel corridor. They concluded that topography 

was an important factor influencing crossing locations 

because caribou tended to fo How ridges and streams 

in their study areas. Noel et al. (2002) found that the 

number of caribou crossing the Badami pipeline did not 

differ significantly between paired sites at river channels and at riparian tundra habitats nearby ( ~0.2-0.6 km 

apart); that study was not designed to compare riparian 

areas with tundra habitats away from rivers. Carruthers 
I 

I 

et al. ( 1984) and Carruthers andJakimchuk (1987) found 

that the habitat characteristics and vegetation at crossing sites used by the Nelchina Caribou Herd did not 

differ from those in the surrounding area. 

Because the surface of the ground is not flat or even, 

a pipeline elevated to 1.5 m at adjacent VSMs may be 

closer to the ground in the intervening interval than at 

the VSMs. In practice, however, there are no indications that this a problem, as microtopography rarely 

rises and falls abruptly within a span of 18 m. In fact, 

the opposite appears to be true in the Kuparuk field, 

where the 1.5-m minimum height has resulted in average heights greater than 1.5 m (Curatolo and Murphy 

1986). Comprehensive data on the range and average 

of pipeline heights in the North Slope oilfields has not 

be5;::n compiled, but would provide valuable information 

for oilfield management and planning. 

Habitat effects may be expressed differently in different seasons. Snow depth differed according to habitat 

type in the snow accumulation study by Pullman and 

Lawhead (2002) on the western North Slope. Snow 

accumulations under pipelines were greater where they 

passed through thaw basins than on adjacent tundra. 

Habituation 

Habituation is the waning over time of response to 

a stimulus after repeated exposure (Cronin et al. 1994, 

Murphy and Lawhead 2000). Over the years, a number of researchers (Child 1973, 1974; Cameron and 

Whitten 1976; Roby 1978; Curatolo and Murphy 1986; 

Shideler 1986) recognized that individuals may react 

differently to infrastructure after repeated exposure, 

but that effect is difficult to measure. Researchers who 

have worked on the North Slope for the past several 

decades have noted that CAH caribou appear to have 

habituated to certain aspects of the infrastructure (Murphy and Lawhead 2000), as evidenced by the lower 

frequency now of strong instantaneous reactions to 

overhead pipe than was observed in the first few years 

of development in the Kuparuk field (Curatolo et al. 

1982; Curatolo and Murphy 1983, 1986). Quantitative 

comparisons have not been conducted to compare the 

current reactions of CAH caribou with those recorded 

in the early 1980s. Habituation to human structures and 

activities likely depends on the perception of threat by 

caribou, and there is no evidence to suggest that maternal cows have habituated to vehicles when their calves 

are less than ~3 weeks old (Lawhead et al. 2004). This 

lack of habituation to predator-like stimuli is reasonable in an evolutionary context because animals that 

habituate to such stimuli are likely to have lower survival. 

In addition to considering other confounding factors 

such as traffic and insect harassment, the responses of 

caribou to elevated pipelines among studies should 

be interpreted in the context of previous exposure to 

infrastructure. The use of significantly higher pipeline for crossings in one plot studied by Curatolo and 

Murphy (1986) occurred in the first year after the 

Kuparuk pipeline was built; no selection was noted 

the next year. The difficulty experienced by two 

large groups of CAH caribou attempting to cross the 

Kuparuk pipeline/road corridor (Smith and Cameron 

1985b) occurred in the first and second summers after 

that pipeline was built. Currently, it is likely that all of 

the adult and yearling members of the CAH encountering elevated pipelines each year have done so before, 

and the majority of older adults probably have encountered infrastructure annually for years, whereas the 

Teshekpuk Caribou Herd (TCH) has had little exposure to oilfield infrastructure. For instance, anecdotal 

observations of Teshekpuk Herd animals south of the 

Prudhoe Bayfield in fall 2003 revealed numerous strong 

behavioral responses to traffic on the Dalton Highway 

(R. Shideler, ADFG, pers. comm.). The available evidence indicates that the behavioral reactions of caribou 

to infrastructure are greater in the first few years of 

encounters than later on; the rate of habituation cannot 

be estimated with confidence but is likely to depend on 

the frequency and duration of encounters. 

CONCLUSIONS 

The evaluation of crossing success for caribou encountering pipeline/road corridors is complicated by 

the interaction of the factors described in this report 

and by the complex group dynamics of caribou, especially during the summer insect season. Except for low 

pipelines elevated ~ 1 m or less, it is difficult to isolate 

pipeline height as a separate variable in the analysis of 

crossing success, so the evaluations performed to date 

have necessarily focused on comparisons of the height 

of pipe at locations crossed by caribou, rather than being 

able to conclusively identify the specific contribution 

of pipe height to crossing success or failure. 

After examining the available literature, we conclude 

that pipelines elevated to the minimum height of 1.5 m 

are high enough to accommodate crossings by caribou 

during snow-free periods, corroborating the conclusions 

of Curatolo and Murphy ( 1986), Lawhead etal. ( 1993a), 

and Cronin et al. (1994). Data supporting the selection 

by caribou of pipeline higher than 1.5 m during snowfree periods were scant, limited to specific locations in 

single years of multi-year studies in the Kuparuk and 

Endicott areas (Curatolo and Murphy 1986, Lawhead 

15 
et al. 1993a). Our reanalysis of caribou crossings in the 

pipe-height categories of 150-1 99 cm versus ~200 cm 

in the Endicott study area does not support the conclusion by Cronin et al. ( 1994) that the higher category 

was selected by caribou. To be as effective as possible, 

elevated pipelines should be separated at or beyond the 

recommended minimum distances of 122-152 m from 

roads experiencing moderate to high levels of traffic 

(Curatolo and Reges 1986, Cronin et al. 1994). The 

available data (Curatolo and Murphy 1986) indicate 

that elevating pipelines to the 1.5-m minimum at VSMs 

results in average heights that are greater than 1.5 m. 

When constructing pipelines, the minimum height should 

be measured at the VSMs rather than being averaged 

over the length of the pipeline. 

The ability of the 1.5-m minimum height to accommodate caribou crossings in winter has assumed greater 

importance recently due to the year-round presence 

of portions of the Teshekpuk Caribou Herd in areas 

of NPR-A that currently are being leased, explored, 

and developed. The limited data available on winter 

crossings (Cameron and Whitten 1976, 1977, 1978; 

Roby 1978; Eide et al. 1986; Carruthers et al. 1987) 

indicate that pipeline heights in the range of2. l-2.5 m 

are more likely to be crossed by caribou than are lower 

heights. Therefore, the minimum pipeline height of 2.1 

m recently mandated by BLM for NPR-A development 

is supported by the available data. 

Because of the tendency for greater snow depths to 

accumulate beneath lower pipe (Pullman and Lawhead 

2002), elevating pipelines higher than 1.5 m will decrease the risk of reduced clearance between the snow 

surface and the bottom of pipelines, especially in severe 

winters. In addition to reducing traffic interference with 

caribou crossings, separating roads from pipelines also 

achieves the important purpose of eliminating snow 

drifts under pipelines next to roads. 

A promising method to address the selection of pipeline height by caribou would be to compare detailed 

movement tracks of caribou collared with GPS transmitters with detailed digital elevation data for ground 

surface and infrastructure, thus allowing collection of 

data over large areas without being confined to study 

plots. This analysis should be possible for the existing 

North Slope oilfields, and perhaps portions of TAPS, 

and could be verified and corrected by field measurements of pipeline height. This approach would have 

the disadvantage of not observing caribou behavioral 

responses to elevated pipelines, however. Where road 

networks are present, the effectiveness of behavioral 

observations would be enhanced by using focal-group 

sampling during road surveys ( Johnson and Lawhead 

16 

1989) to follow groups until they cross or retreat, rather 

than by using plot-based tower observations. 

Observational studies of existing pipelines have inherent limitations. To truly determine the optimal 

pipeline height for caribou passage, more experimental studies would need to be conducted. Experimental 

manipulations of pipe height using realistic simulations that can be varied in height would be useful as 

well (Cronin et al. 1994), but would pose practical 

problems. Ideally these studies would change pipeline 

heights in the same area at different times or provide 

a variety of available pipeline heights within one area 

with multiple replicates. 

Research Needs 

The pace of mitigation-related research on caribou 

crossing success at pipeline/road corridors in the 1990s 

declined from the 1970s and 1980s, so the accumulation of information on the success of caribou crossing 

pipelines has slowed as well. The mitigation research 

conducted since the early 1990s focused on questions 

other than pipeline height, such as the effect of oscillation dampeners and riparian corridors (Coltrane and 

Lanctot 2001, Noel et al. 2002), snow depth under 

elevated pipelines (Pullman and Lawhead 2002), and 

traffic convoying as a potential measure to decrease 

displacement of maternal caribou with young calves 

(Lawhead et al. 2004). Nevertheless, the topic has been 

a prominent one for local residents on the North Slope 

of Alaska as development has spread westward, and 

more questions and ideas for further research became 

evident during this literature review. The following 

list presents our view of needs for further infonnation 

regarding the effects of pipeline height on caribou 

crossing success. 

l)Adequacyof 1.5-m-highpipeline inwinte1: Shideler 

( 1986) identified this as a research need in his review 

nearly 20 years ago. The study by Pullman and Lawhead 

(2002) is the only one to address pipeline clearance in 

winter on the Arctic Coastal Plain, and it contained no 

information on caribou crossings. This issue is important 

for development in NPR-A because of the year-round 

presence of members of the TCH on the coastal plain 

(Philo et al. 1993, Prichard et al. 2001, Prichard and 

Murphy 2004), in contrast to the CAH, which winters 

far south of the oilfields. The available data from studies of TAPS pipeline crossings indicate that pipelines 

elevated to 2.1-2.5 mare high enough to accommodate 

crossings in winter, but those data are scant. Studying 

caribou crossings in winter would be difficult due to 

the constraints imposed by weather, short days, and 

low movement rates by caribou, so such an analysis 
would best be done retrospectively hy examining the 

characteristics of pipelines in areas that were crossed 

by caribou equipped with GPS collars. 

2) Effects of habituation. This issue is especially 

relevant to development in NPR-A because of the difference between CAH caribou, which are experienced 

at negotiating infrastructure, and TCH caribou, which 

are relatively nai"ve and have had little exposure to 

linear developments. It will be important to document 

the behavioral responses of TCH caribou early in the 

NPR-A developrncnl process because the greatest 

behavioral effects are most I ikely to occur then, judging 

from the CAH experience. For the CAH, behavioral 

studies could be repeated to quantify changes over 

time in the proportions of strong reactions, but repeating studies in old sites~e.g., the Kuparuk sites used 

hy Curatolo and Murphy (1986) or the Sagavanirktok 

River delta sites studied by Fancy ( 1983) and Lawhead 

et al. (l 993a)~\vould be difficult because additional 

infrastructure has been added since those studies were 

done. 

3) Refiectivitv ojj)ipeline sheathing This factor has 

not been evaluated because it emerged in public testimony and pennitting discussions relatively recently, 

and nonreflectivc sheathing has been used in only one 

project to date (Kuparuk DS-3S). Therefore, the options for designing a study to assess this design feature 

are limited; the DS-3S pipeline is elevated to 2.1 m, 

so discriminating between the effect of sheathing and 

the effect of higher pipe would be problematic. The 

nonreileetivc pipeline does not shine as brightly in the 

sun as the older reflective sheathing, but the profile of 

the pipeline overhead is identical to other pipelines. In 

the final analysis, pipeline reflectivity is an issue that 

involves visual effects on humans as much as on caribou, so taking measures to reduce it would be a proactive 

measure to mitigate the concerns of local residents at 

little or no additional cost. 

4) Other confi:mnding factors. The emphasis in 

mitigation-related research has been placed on factors 

that were reasonably simple to observe and quantifymainly visual stimuli-but the potential contribution of 

other stimuli is unknown ( e.g., Banfield et al. 1981 ). For 

instance, the effects of noise (from wind and irregular 

flow of fluids through pipelines) and olfactory influences such as "pheromone trails" and alarm signals from 

previous groups passing through an area (Muller 

-Schwarze et al. 1979) have not been evaluated. It is 

unknown whether these additional factors, which would 

be difficult to isolate from the overall effect of an overhead structure, could cause deflections if sudden noises 

from an overhead pipeline or olfactory indications of 

previous disturbances startle and delay caribou trying 

to cross. 

5) Adequacy ojjJipeline heightj[Jr subs;.s•tence users. 

In the final analysis, elevated pipelines constructed 

in areas used by subsistence hunters and trappers or 

hy other travelers using snowmobiles must be high 

enough to safely allow crossings beneath the pipes. 

Pullman and Lawhead (2002) estimated that clearance 

or 1.4-1.5 rn between the snow surface (disregarding compaction by the machine) and the bottom of a 

pipeline was the minimum safe height for this purpose. 

Thus, the decision to build pipelines higher than 1 .5 rn 

must consider this need as well as caribou crossing 

success, but the solution to both problems may be the 

same. Pipelines high enough to safely accommodate 

snowmobile riders in the deepest winter snows also 

should be high enough to allow crossings by caribou 

under those conditions. 

17 

LITERATURE CITED 

Banfield, A. W. F., R. D. J akimchuk, and R. D. Cameron. 

1981. An assessment of issues concerning caribou and 

North Slope petroleum development. Caribou Advismy Panel final report, prepared for ARCO Alaska, 

Inc.; Chevron USA , Inc.; Conoco, Inc.; Exxon Co., 

USA; Shell Oil Co.; and SOHIO Alaska Petroleum 

Co., Anchorage, AK. 34 pp. + attachments. 

Bergerud,A. T., R. D. Jakimchuk, and D.R. Carruthers. 

1984. The buffalo of the north: Caribou (Rangifer 

tarandus) and human developments. Arctic 37: 7-22. 

BLM (Bureau of Land Management). 1998. Northeast 

National Petroleum Reserve-Alaska: Final Integrated 

Activity Plan I Environmental Impact Statement. Vol. 

1. U.S. Department of the Interior, Bureau of Land 

Management, with assistance from Minerals Management Service, Anchorage, AK. 

BLM. 2002. Final Environmental Impact Statement: 

Renewal of the Federal Grant for the Trans-Alaska 

Pipeline System Right-of- Way. Vols. 1-6. BLM/ AKI 

PT-03/005+2880+ 990. U.S. Department of the Interior, Bureau of Land Management, Anchorage, AK. 

BLM. 2004. Alpine Satellite Development Plan Final 

Environmental Impact Statement. Vols 1-3. U.S. Department of the Interior, Bureau of Land Management, 

Anchorage, AK. 

BLM. 2005. Northeast National Petroleum ReserveAlaska: Final Amended Integrated Activity Plan / 

Environmental Impact Statement. Vols. 1-3. U.S. Department of the Interior, Bureau of Land Management, 

Anchorage, AK. 

Byers, C. R., R. K. Steinhorst, and P. R. Krausman. 

1984. Clarification of a technique for analysis of utilization-availability data. Journal of Wildlife Management 48: 1050-1053. 

Cameron, R. D., D. J. Reed, J. R. Dau, and W. T. Smith. 

1992. Redistribution of calving caribou in response to 

oil field development on the ~retie Slope of Alaska. 

Arctic 45: 338-342. 

Cameron, R. D., and K. R. Whitten. 1976. First interim 

report of the effects of the Trans-Alaska Pipeline on 

caribou movements. Special Report Number 2. Joint 

State/Federal Fish & Wildlife Advisory Team, Anchorage, AK. 39 pp. 

Cameron, R. D., and K. R. Whitten. 1977. Second interim report of the effects of the Trans-Alaska Pipeline on caribou movements. Special Report Number 

8. Joint State/Federal Fish & Wildlife Advisory Team, 

Anchorage, AK. 34 pp. 

Cameron, R. D., and K. R. Whitten. 1978. Third interim report of the effects of the Trans-Alaska Pipeline 

on caribou movements. Special Report Number 22. 

Joint State/Federal Fish & Wildlife Advisory Team, 

Anchorage, AK. 29 pp. 

Carruthers, D. R., and R. D. Jakimchuk. 1987. Migratory movements of the Nelchina caribou herd in relation to the Trans-Alaska pipeline. Wildlife Society 

Bulletin 15: 414-420. 

Carruthers, D.R., R. D. Jakimchuk, and C. Linkswiler. 

1984. Spring and fall movements ofNelchina caribou 

in relation to the Trans-Alaska Pipeline. Report prepared for Alyeska Pipeline Service Company, Anchorage, by Renewable Resources Consulting Services 

Ltd., Sidney, BC. 102 pp. 

Child, K. N. 1973. Reaction of barren-ground caribou 

(Rang?fer tarandus granti) to simulated pipeline and 

pipeline crossing structures at Prudhoe Bay, Alaska. 

Report prepared for Alyeska Pipeline Service Company and British Petroleum Alaska, Inc. by Alaska 

Cooperative Wildlife Research Unit, University of 

Alaska, Fairbanks. 51 pp. 

Child, K. N. 1974. Reactions of caribou to various 

types of simulated pipelines at Prudhoe Bay, Alaska. 

Pages 805-812 in V. Geist and F. Walther, editors. The 

Behaviour of Ungulates and its Relation to Management. Vol. 2. International Union for the Conservation 

of Nature and Natural Resources, Publications New 

Series, No. 24, Morges, Switzerland. 

19 
Child, K. 1975. A specific problem: The reaction of 

reindeer and caribou to pipelines. Pages 14-32 in J. R. 

Luick, P. C. Lent, D. R. Klein, and R. G. White, editors. Proceedings of the First International Reindeer/ 

Caribou Symposium, 9-11 August 1972, University 

of Alaska, Fairbanks. Biological Papers of the University of Alaska, Special Rep01i No. 1. 

Child, K. N., and P. C. Lent. 1973. The reactions ofreindeer to a pipeline simulation at Penny River, Alaska. 

Interim repm1 by Alaska Cooperative Wildlife Research 

Unit, University of Alaska, Fairbanks. 29 pp. 

Coltrane, J. A., and R. B. Lanctot. 2001. The effect 

of vibration dampers on caribou (Rang[fer tarandus) 

crossing success rate under the elevated Badami pipeline, Alaska, 1999. Final report prepared for BP Exploration (Alaska) Inc., by LGL Alaska Research Associates, Inc. 20 pp. 

Cronin, M. A., W. B. Ballard, J. Truett, and R. Pollard. 1994. Mitigation of the effects of oil-field development and transportation corridors on caribou. Final 

report to the Alaska Caribou Steering Committee, prepared for Alaska Oil and Gas Association, U.S. Fish 

and Wildlife Service, Alaska Department of Fish and 

Game, and the Nmih Slope Borough, by LGL Alaska 

Research Associates, Inc., Anchorage. 24 pp.+ appendices. 

Curatolo, J. A. 1984. A study of caribou response to 

pipelines in and near the Eileen West End, 1983. Final 

report prepared for Sohio Alaska Petroleum Company, 

Anchorage, by Alaska Biological Research, Fairbanks. 

32 pp. 

Curatolo, J. A., and S. M. Murphy. 1983. Caribou 

responses to the pipeline/road complex in the Kuparuk Oil Field, Alaska, 1982. Final report prepared for 

ARCO Alaska, lnc., Anchorage, by Alaska Biological 

Research, Fairbanks. 81 pp. 

Curatolo, J. A., and S. M. Murphy. 1986. The effects 

of pipelines, roads, and traffic on the movements of 

caribou, Rang(fer tarandus. Canadian Field-Naturalist 

100: 218-224. 

Curatolo, J. A., S. M. Murphy, and M.A. Robus. 1982. 

Caribou responses to the pipeline/road complex in the 

Kuparuk Oil Field, Alaska, 1981. Final report prepared for ARCO Alaska, Inc., Anchorage, by Alaska 

Biological Research, Inc., Fairbanks. 63 pp. 

20 

Curatolo, J. A., and A. E. Reges. 1986. Caribou use 

of pipeline/road separations and ramps for crossing 

pipe/road complexes in the Kuparuk Oilfield, Alaska, 

1985. Final report prepared for ARCO Alaska, Inc., 

and Kuparuk River Unit, Anchorage, by Alaska Biological Research, Fairbanks. 106 pp. 

Dau, J. R., and R. D. Cameron. 1986. Effects of a road 

system on caribou distribution during calving. Rangifer, 

Special Issue No. 1: 95-101. 

Dyer, S. J. 1999. Movement and distribution of woodland caribou (Rangffer tarandus caribou) in response 

to industrial development in northeastern Alberta. M.S. 

thesis, University of Alberta, Edmonton. 106 pp. 

Dyer, S. J., J.P. O'Neill, S. M. Wasel, and S. Boutin. 

2002. Quantifying barrier effects of roads and seismic 

lines on movements of female woodland caribou in 

northeastern Alberta. Canadian Journal of Zoology 

80: 839-845. 

Eide, S. H., S. D. Miller, and M.A. Chihuly. 1986. Oil 

pipeline crossing sites utilized in winter by moose and 

caribou in southccntral Alaska. Canadian Field-Naturalist 100: 197-207. 

Fancy, S. G. 1982. Movements and activities of caribou at Drill Sites 16 and 17, Prudhoc Bay, Alaska: the 

second year. Final report prepared for Prudhoe Bay 

Unit Owners by LGL Alaska Research Associates, 

Inc. 48 pp. 

Fancy, S. G. 1983. Movements and activity budgets 

of caribou near oil drilling sites in the Sagavanirktok 

River floodplain, Alaska. Arctic 36: 193-197. 

Fancy, S. G ., R. J. Douglass, and J. M. Wright. 1981. 

Movements and activities of caribou at Drill Sites I 6 

and 17, Prudhoe Bay, Alaska. Final report prepared for 

Prudhoc ,Bay Unit Owners by LGL Alaska Research 

Associates, Inc. 48 pp. 

Forbes, B. C. 1999. Reindeer herding and petroleum 

development on Poluostrov Yamal: Sustainable or mutually incompatible uses? Polar Record 35: 317-322. 

Gilders, M. A., and M. A. Cronin. 2000. North Slope 

oil field development. Chapter 2, Pages 15-33 in J. 

Truett and S. R. Johnson, editors. The Natural History 

of an Arctic Oil Field: Development and the Biota. 

Academic Press, San Diego, CA. 
Hanson, W. C. 1981. Caribou (Rangffer tarandus) encounters with pipelines in northern Alaska. Canadian 

Field-Naturalist 95: 57-62. 

Hemming, J.E. Undated. Wild reindeer and pipelines 

in north central Siberia. Unpublished report of an exchange visit under terms of USA/USSR Environmental Protection Agreement. Project V-2 Ecosystems of 

Northern Regions. 8 pp. 

Jakimchuk, R. D. 1980. Disturbance to barren-ground 

caribou: A review of the effects and implications of 

human developments and activities. Report prepared 

for Polar Gas Project by R. D. Jakimchuk Management Associates Ltd., Sidney, BC. 140 pp. 

Jalkotzy, M. G., P. I. Ross, and E. M. D. Nasserden. 

1997. The effects of linear developments on wildlife: 

A review of selected scientific literature. Report prepared for Canadian Association of Petroleum Producers, by Arc Wildlife Services Ltd., Calgary, AB. 119 

pp. 

James, A. R. C., and A. K. Stuart-Smith. 2000. Distribution of caribou and wolves in relation to linear corridors. Journal of Wildlife Management 64: 154-159. 

Johnson, C. B., and B. E. Lawhead. 1989. Distribution, 

movements, and behavior of caribou in the Kuparuk 

Oilfield, summer 1988. Final report prepared for ARCO 

Alaska, Inc. and Kuparuk River Unit, Anchorage, by 

Alaska Biological Research, Inc., Fairbanks. 71 pp. 

Klein, D.R. 1971. Reaction ofreindeer to obstructions 

and disturbances. Science 173: 393-398. 

Klein, D. R. Undated. Ecology and management of 

wild and domestic reindeer in Siberia. Unpublished 

report of an exchange visit under terms of USA/USSR 

Environmental Protection Agreement. Project V-2 

Ecosystems of Northern Regions. 

Klein, D. R. 1980. Reaction of caribou and reindeer 

to obstructions-A reassessment. Pages 519-527 in E. 

Reimers, E. Gaare, and S. Skjenneberg, editors. Proceedings of the Second International Reindeer/Caribou 

Symposium. 17-21 September 1979, R0ros, Norway. 

Direktoratet for vilt og ferskvannsfisk, Trondheim, 

Norway. 

Lawhead, B. E. 1988. Distribution and movements of 

Central Arctic Herd caribou during the calving and insect seasons. Pages 8-13 in R. Cameron and J. Davis, 

eds. Reproduction and calf survival: Proceedings of 

the Third North American Caribou Workshop. Wildlife Technical Bulletin No. 8, Alaska Department of 

Fish and Game, Juneau. 

Lawhead, B. E., L. C. Byrne, and C. B. Johnson. 1993a. 

Caribou synthesis, 1987-1990. 1990 Endicott Environmental Monitoring Program Final Report, Vol. V. U.S. 

Army Corps of Engineers, Alaska District, Anchorage. 

Final report prepared for Science Applications International Corporation, Anchorage, by ABR, Inc., Fairbanks. 

114 pp. 

Lawhead, B. E., and D. A. Flint. 1993. Caribou movements in the vicinity of the planned Drill Site 3-T facilities, Kuparuk Oilfield, Alaska, 1991-92. Progress 

report prepared for ARCO Alaska, Inc. and the Kuparuk River Unit, Anchorage, by Alaska Biological Research, Inc., Fairbanks. 62 pp. 

Lawhead, B. E., C. B. Johnson, and L. C. Byrne. 

1993b. Caribou surveys in the Kuparuk Oilfield during 

the 1993 calving and insect seasons. Final report prepared for ARCO Alaska, Inc., and the Kuparuk River 

Unit, Anchorage, by Alaska Biological Research, Inc., 

Fairbanks. 38 pp. 

Lawhead, B. E., A. K. Prichard, M. J. Macander, and 

M. Emers. 2004. Caribou mitigation monitoring study 

for the Meltwater Project, 2003. Third annual report 

prepared for ConocoPhillips Alaska, Inc., Anchorage, 

by ABR, Inc., Fairbanks. 104 pp. 

LeResche, R. E., and S. A. Linderman. 1975. Caribou 

trail systems in northeastern Alaska. Arctic 28: 54-

61. 

McCourt, J., D. Feist, D. Doll, and J. J. Russell. 1974. 

Disturbance studies of caribou and other mammals in 

the Yukon and Alaska, 1972. Arctic Gas Study Ltd., 

Biological Report Series, Vol. 5. [ cited in Jakimchuk 

1980] 

Miller, F., C. J. Jonkel, and G. D. Tessier. 1972. Group 

cohesion and leadership response by barren-ground 

caribou to man-made barriers. Arctic 25: 193-202. 

Muller-Schwarze, D., L. Kallquist, and T. Mossing. 

1979. Social behavior and chemical communication in 

reindeer (Rangifer t. tarandus L.). Journal of Chemical 

Ecology 5: 483-517. 

21 
Murphy, S. M. 1984. Caribou use of ramps for crossing pipe/road complexes, Kuparuk Oilfield, Alaska, 

1984. Final report prepared for ARCO Alaska, Inc., 

Anchorage, by Alaska Biological Research, Fairbanks. 

61 pp. 

Murphy, S. M., and J. A. Curatolo. 1984. Responses 

of caribou to ramps and pipelines in the west end of 

the Kupamk Oil Field, Alaska, 1983. Final report prepared for ARCO Alaska, Inc., Anchorage, by Alaska 

Biological Research, Fairbanks. 41 pp. 

Murphy, S. M., and J. A. Curatolo. 1987. Activity 

budgets and movement rates of caribou encountering 

pipelines, roads, and traffic in northern Alaska. Canadian Journal of Zoology 65: 2483-2490. 

Murphy, S. M., and B. E. Lawhead. 2000. Caribou. 

Chapter 4, Pages 59-84 in J. Truett and S. R. Johnson, 

editors. The Natural History of an Arctic Oil Field: 

Development and the Biota. Academic Press, San Diego, CA. 

Neu, C. W., C.R. Byers, J.M. Peek, and V. Boy. 1974. 

A technique for analysis of utilization-availability 

data. Journal of Wildlife Management 38: 541-545. 

Noel, L. E., M. J. Nemeth, and B. J. Streever. 2002. 

Chapter 4 in M. A. Cronin, editor. Arctic Coastal Plain 

caribou distribution, summer 2001. Report prepared 

for BP Exploration (Alaska) Inc., Anchorage, by LGL 

Alaska Research Associates, Inc., Anchorage. 

NRC (National Research Council). 2003. Cumulative 

Environmental Effects of Oil and Gas Activities on 

Alaska's North Slope. National Academies Press, 

Washington, D.C. 288 pp. 

Oberg, P. R. 2001. Responses of mountain caribou to 

linear features in a west-central Alberta landscape. 

M.S. thesis, University of Alberta, Edmonton. 126 

pp. 

PAI (Phillips Alaska, Inc.). 2001. Caribou mitigation 

plan for the Meltwater Project on the North Slope of 

Alaska, 2001. Prepared for U.S. Army Corps of Engineers, Anchorage, AK. 

Philo, L. M., G. M. Carroll, and p. A. Yokel. 1993. 

Movements of caribou in the Teshekpuk Lake Herd 

as determined by satellite tracking, 1990--1993. Un22 

published report, North Slope Borough Department of 

Wildlife Management, Barrow; Alaska Department of 

Fish and Game, Barrow; and U.S. Department oflnterior, Bureau of Land Management, Fairbanks. 60 pp. 

Pollard, R. H., P. C. Lent, M. E. Miller, and R. C. 

Wilkinson. 1992. Caribou distribution in the Prudhoe Bay, Kuparuk, and Milne Point oil fields, summer 1991. Northern Alaska Research Studies report 

prepared for BP Exploration (Alaska) Inc., Anchorage, by LGL Alaska Ecological Research Associates, 

Anchorage. 25 pp. 

Pollard, R. H., and L. E. Noel. 1994. Caribou distribution and parasitic insect abundance in the Prudhoe Bay 

Oil Field, summer 1993. Northern Alaska Research 

Studies report prepared for BP Exploration (Alaska) 

Inc., Anchorage, by LGL Alaska Ecological Research 

Associates, Anchorage. 80 pp. 

Prichard, A. K., and S. M. Murphy. 2004. Analysis and 

mapping of satellite telemetry data for the Teshekpuk 

Caribou Herd, 1990--2002. Final report prepared for 

North Slope Borough Department of Wildlife Management, Barrow, by ABR, Inc., Fairbanks. 110 pp. 

Prichard, A. K., S. M. Murphy, and M. D. Smith.2001. 

Analysis and mapping of satellite telemetry data for 

the Teshekpuk Caribou Herd, 1990-1999, with a note 

on five Western Arctic caribou. Report prepared for 

North Slope Borough Department of Wildlife Management, Barrow; Alaska Department of Fish and 

Game, Barrow; and U.S. Department of the Interior, 

Bureau of Land Management, Fairbanks, by ABR, 

Inc., Fairbanks. l 02 pp. 

Pullman, E. R., and B. E. Lawhead. 2002. Snow depth 

under elevated pipelines in western North Slope oilfields. Final report prepared for Phillips Alaska, Inc., 

Anchorage, by ABR, Inc., Fairbanks. 19 pp. 

Reges, A. E., and J. A. Curatolo. 1985. Behavior of 

caribou encountering a simulated low-elevation pipeline. Final report prepared for ARCO Alaska, Inc., Anchorage, by Alaska Biological Research, Fairbanks. 

17 pp. 

Roby, D. D. 1978. Behavioral patterns of barrenground caribou of the Central Arctic Herd adjacent to 

the Trans-Alaska Oil Pipeline. M.S. thesis, University 

of Alaska, Fairbanks. 200 pp. 
Shank, C. C. 1979. Human-related behavioural disturbance to northern large mammals: A bibliography and 

review. Alaska Highway Gas Pipeline Project report 

prepared for Foothills Pipe Lines (South Yukon) Ltd., 

Calgary, AB. 254 pp. 

Shideler, R. T. 1986. Impacts of human developments 

and land use on caribou: A literature review. Volume II 

- Impacts of oil and gas development on the Central 

Arctic Herd. Technical Report No. 86-3. Alaska Department of Fish and Game, Juneau. 128 pp. 

Skrobov, V. D. 1972. Man and the wild reindeer on 

Taimyr. Priroda 72: 98-99. [translated from Russian] 

Smith, W. T., and R. D. Cameron. 1985a. Factors affecting pipeline crossing success of caribou. Pages 

40-46 in A. Martell and D. Russell, editors. Caribou 

and human activity: Proceedings of the First North 

American Caribou Workshop, 28-29 September 1983, 

Whitehorse, Y.T. Canadian Wildlife Service, Ottawa. 

68 pp. 

Smith, W. T., and R. D. Cameron. 1985b. Reactions 

of large groups of caribou to a pipeline corridor on the 

Arctic Coastal Plain of Alaska. Arctic 38: 53-57. 

Smith, W. T., R. D. Cameron, and D. J. Reed. 1994. 

Distribution and movements of caribou in relation 

to roads and pipelines, Kuparuk Development Area, 

1978-1990. Wildlife Technical Bulletin No. 12. Alaska 

Department of Fish and Game, Juneau. 54 pp. 

Thompson, D. C., K. H. McCourt, and R. D. Jakimchuk. 

1978. An analysis of the concerns for the Porcupine 

Caribou Herd in regard to an elevated pipeline on the 

Yukon coastal plain. Report prepared for Dome Petroleum Ltd., by Renewable Resources Consulting Services Ltd. 88 pp. 

White, R. G., B. R. Thomson, T. Skogland, S. J. Person, 

D. E. Russell, D. F. Holleman, and J. R. Luick. 1975. 

Ecology of caribou at Prudhoe Bay, Alaska. Pages 

151-201 in J. Brown, editor. Ecological investigations of the tundra biome in the Prudhoe Bay region, 

Alaska. Biological Papers of the University of Alaska, 

Special Report No. 2. 

Whitten, K. R., and R. D. Cameron. 1986. Groups versus individuals in the detennination of caribou distribution. Rangifer, Special Issue 1: 325-329. 

WMI (Wildlife Management Institute). 1991. Review 

of North Slope Alaska caribou research. Unpublished 

report to Alaska Department of Fish and Game, Juneau, by Wildlife Management Institute, Washington, 

DC. 51 pp. 

Wolfe, S. A., B. Griffith, and C. A. Gray Wolfe. 2000. 

Response of reindeer and caribou to human activities. 

Polar Research 19: 63-73. 

23 

APPENDIX A. MEASUREMENT UNITS AND ACRONYMS 

Measurement Conversions 

1 m = 3.2808 ft I ft= 0.3048 m 

I in. = 2.54 cm 

5 ft= 1.524 m 

Im= 1.0936 yd 

7 ft= 2.1336 m 

I cm= 0.3937 in. 1 yd= 0.9144 m 

I km= 0.6214 mi 1 mi= 1.6093 km 

I mi2 = 2.590 km2 I km2 = 0.3861 mi2 1 acre= 0.4047 ha I ha= 2.4711 acres 

Acronyms Used 

ADFG 

ADNR 

AOGA 

BLM 

CAH 

DS 

GIS 

GPS 

IAP/EIS 

NPR-A 

NSB 

PVD 

TAPS 

TCH 

TVA 

USFWS 

VSM 

Alaska Department of Fish and Game 

Alaska Department of Natural Resources 

Alaska Oil and Gas Association 

Bureau of Land Management 

Central Arctic Herd 

Drill Site (prefix used in alphanumeric designations of specific gravel pads) 

Geographical Information System 

Global Positioning System 

Integrated Activity Plan/Environmental Impact Statement 

National Petroleum Reserve-Alaska 

North Slope Borough 

Pipeline Vibration Damper (oscillation dampener; see TVA) 

Trans-Alaska Pipeline System 

Teshekpuk Caribou Herd 

Tuned Vibration Absorber ( oscillation dampener; see PVD) 

U.S. Fish & Wildlife Service 

Vertical Support Member 

25 

APPENDIX B. EXPERTS CONSUL TED 

Raymond D. Cameron 

ADFG (emeritus) and University of Alaska, 

Fairbanks 

Kenneth N. Child 

BC Hydro (emeritus), Prince George, BC 

Bruce C. Forbes 

Arctic Centre, University of Lapland, Rovanemi, 

Finland 

Anne Gunn 

G9vernment of the Northwest Territories, 

Yellowknife, NT 

David R. Klein 

University of Alaska, Fairbanks (emeritus) 

Derek A. Melton and Carol Stefan 

Golder Associates Ltd., Calgary, AB 

No response received: 

Margarita Magomedova 

Institute of Plant and Animal Ecology, Ekaterinburg, 

Russia 

John A.Nagy 

Government of the Northwest Territories, Inuvik, NT 

Paula Pacholek 

Joint Review Panel for the Mackenzie Gas 

Project, Inuvik, NT 

Christian Nellemann 

UNEP GRID-Arendal/NINA, Lillehammer, Norway 

Lynn Noel 

ENTRIX, Inc., Anchorage, AK 

Don E. Russell 

Canadian Wildlife Service, Environment Canada, 

Whitehorse, Yukon 

Fiona K. A. Schmiegelow 

Department of Renewable Resources, University of 

Alberta, Edmonton 

Kirby Smith 

Fish and Wildlife Division, Alberta Sustainable 

Resource Development 

27 

APPENDIX C. INFRASTRUCTURE IN ALASKA NORTH SLOPE OILFIELDS 

Elevated pipelines (Figure C-1) are used throughout 

the North Slope oilfields, both for mixed-phase ( oil, 

gas, and water) gathering lines from drill sites to and 

from processing facilities and also for shipment of 

sales-quality oil to TAPS via the Kuparuk, Endicott, 

Alpine, and Badami pipelines. The gathering pipelines 

constructed in the original Prudhoe Bay field were 

low, elevated only to heights of 0.4-1.1 m (Smith and 

Cameron 1985a, Shideler 1986). That height range 

was determined to be inadequate to allow free passage 

by caribou ( as is discussed earlier in this review), so 

a standard minimum height of 1.5 m above ground 

level was established by the State of Alaska in 1979 

(Shideler 1986), as oil development was beginning 

to expand beyond the original Prudhoe Bay field. All 

of the pipelines west of the Kuparuk River were constructed to meet this minimum-height requirement. In 

the early 1980s, ADFG and the Alaska Department 

of Natural Resources (ADNR) debated whether new 

pipelines planned for the Milne Point field should be 

raised higher to 2 .1 m above ground level, but the lower 

height was chosen. Short sections of pipeline elevated 

to 2.4 m were proposed to be constructed as mitigative 

measures on the gathering lines for Kuparuk DS-3T, a 

project for which baseline data on caribou movement 

patterns were collected (Lawhead and Flint 1993) but 

which was never constructed. 

Not all pipelines in the North Slope oilfields are elevated. Some gather_ing pipelines were buried within 

road berms (which are themselves elevated ""1.5 m 

above ground level, depending on terrain) in portions 

of the Milne Point oilfield constructed in the mid- to 

late 1980s by Conoco, Inc., the original developer of 

the Milne Point field. That design has not been used 

subsequently by BP Exploration (Alaska) Inc., the current operator of the Milne Point field, or by ConocoPhillips Alaska, Inc. (formerly Phillips Alaska and 

ARCO Alaska) on its recent projects in the western 

Kuparuk field, primarily due to concerns about thermal and structural stability, spill. detection, and the 

increased amount of gravel needed to construct road 

berms thick eno,ugh to accommodate buried pipelines. 

Gravel crossing ramps were constructed in the 

Prudhoe Bay, Kuparuk, and Milne Point fields and 

along the Endicott pipeline/road corridor. Ramps are 

specially constructed, short (typically ~30 m) stretches 

of gravel placed over low pipe to enhance crossing success by caribou (Murphy 1984, Murphy and Curatolo 

1984, Curatolo and Murphy 1986, Shideler 1986, Cronin 

et al. 1994). The rationale for ramps came from early 

studies (Child 1973, Cameron and Whitten 1976, 1977, 

1978) that suggested that caribou preferentially crossed 

over elevated pipelines at buried sections. Short ( ~ 18 m) 

sections of buried pipe called "sag-bends" were placed 

at intervals along the TAPS, as were short sections of 

higher-than-normal pipe called Designated Big Game 

Crossings (DBGCs) (Eide et al. 1986, BLM 2002). 

Ramps have not been used in new development on the 

North Slope since the late 1980s, having largely been 

replaced as mitigative measures by separating pipelines 

from roads for as much of their length as possible. 

Differences in interpretation regarding the 1.5-m 

minimum height requirement resulted in some discrepancies in pipeline height among projects. Pipelines 

constructed in the Kuparuk and Milne Point fields were 

a minimum height of 1.5 m measured at the VSMs, 

whereas the Endicott pipeline built on the Saga vanirktok 

River delta appeared to have been built to an average 

(rather than a minimum) height of 1.5 m, resulting in 

sections of pipeline along that 16-km corridor that are 

lower than 1.5 m, especially on ridges and other raised 

topographic features (Lawhead et al. 1993a). The 40-

km pipeline built in winter 1997-1998 to connect the 

Badami project facilities to the Endicott pipeline has 

three short stretches of pipe, totaling ~ 182 m ( 600 ft), 

that is lower than the required minimum (Coltrane and 

Lanctot 2001, Noel et al. 2002). 

The diameter of VSMs typically is in the 30-46 cm 

( 12-18 in.) range, but larger diameter supports are used 

in crossing river floodplains such as the Kuparuk and 

Colville. The spacing of intervals between consecutive 

VS Ms typically is in the 12-18 m ( 40-60 ft) range. The 

diameters of pipelines range from ~20 cm (8 in.) up 

to 91-122 cm (36-48 in.), plus ~ 20 cm of additional 

diameter from the insulation covering. 

Most pipeline corridors in the North Slope oilfields 

contain more than one pipe, ranging up to a maximum 

of 26 adjacent pipelines. Single pipelines comprised 

only 16% of the total length of existing corridors in 

200i and 75% of the total length consisted.of four or 

fewer pipelines (NRC 2003: Appendix E). When more 

than about 6pipes are present, additional pipe racks are 

constructed next to existing racks, adding more width 

to the pipeline corridor and contributing to a tunnel 

effect under the pipelines. The greatest numbers of adjacent pipes typically occur near processing facilities, 

as gathering lines from multiple drill sites converge on 

a central location. 

29 
f 

l ,I~.----- ''"':'!"'-y~----~----~,,-~ {))-r--------- - -----------r-~ ~---------~-- ----------~------/-

--· ~ 

-·-- ; ~; -~--~~~~-I~-j .-· 

--~ ~ I i ... ---~-r-11~~----r 

I I 1 

~; 

1. 

1--...' 

ARCO Al · - . _ aska, . 1· nc. ~~ ,., 

l 

! 

! 

M ODIJL.£: 2PYD 

DS2P 

PVO !NSTAaATlm4 

PIPELINE' 

UNIT: L1 

PVD-5FT--M!N Sf.EH: !REV, 

0010F , 0 

Figure C-1. Elevated pipeline design (2.I~m [7-ft] minimum clearance) with "potato-masher" style oscillation 

dampeners, or TVAs (1.5-m [5-ft] minimum clearance), for the Meltwater Project (Kuparuk DS-2P). Figure 

reproduced from PAI (2001). 

30 
Pipelines are typically located within 20-30 m of roads 

in most of the Prudhoe Bay, Kuparuk, Milne Point, and 

Endicott development areas that were built in the 1970s 

and 1980s. Pipelines in newer developments ( 1990s 

to present) are separated from adjacent roads,. based 

on recommendations from mitigation-related research 

for a minimum distance of 122 m (Curatolo and Reges 

1986) or 152 m (Cronin et al. 1994) and within the 

305-m maximum distance required for leak detection. 

Pipelines in the oilfields typically are located on the 

upslope sides of roads to take advantage of the potential 

spill containment value of the road berm. 

Expansion loops are constructed to accommodate 

thermal expansion and contraction of pipelines throughout the year. Loops usually consist of horizontal elbows 

to allow longitudinal flexing of the pipelines, but vertical loops were used on the Alpine pipeline. Those 

vertical loops were installed to eliminate the need for 

check valves and their attendant potential for corrosion, 

but they also provided short but highly visible, higherthan-nonnal sections of pipeline that potentially could 

be used by caribou. 

Because pipelines arc susceptible to wind-induced 

vibration, oscillation dampeners ( also called pipeline 

vibration dampers, or PVDs, and tuned vibration absorbers, or TV As) often are attached to pipelines (Figure 

C-2). The older design of these devices consisted of a 

heavy metal sphere suspended by an articulated strap, 

but newer designs have been developed to avoid hanging 

down as far-as much as 94 cm (Coltrane and Lanctot 

2001 )-beneath the pipeline. In some locations, the 

newer styles of oscillation dampeners have been attached 

to the top of pipelines instead of beneath them. 

The reflectivity of the metal sheathing used to protect 

pipeline insulation (Figure C-2) has been identified 

as a concern by residents of Nuiqsut and other North 

Slope villages. Because of that concern, a nonreflective, 

dull-finished coating was used on the Kuparuk DS-3S 

("Palm") pipelines constructed in 2002 (Figure C-3). 

Thus far, those pipelines are the only ones with nonreflecti ve sheathing in the North Slope oilfields, and no 

comparisons of crossing success with reflective-coated 

pipelines have been done. 

Figure C-2. Kuparuk DS-2L pipeline elevated to 1.5-m minimum height and showing older spherical style and 

newer "potato-masher" style of vibration oscillation dampeners, and reflectivity of standard sheathing. Photo 

by B. Lawhead, ABR, Inc. Copyright ConocoPhillips Alaska, Inc. 

31 
Figure C-3. Pipelines with nonreflective sheathing and elevated to a mm1mum height of 2.1 m, 

constructed in winter 2001-2002, Kuparuk DS-3S project, northern Alaska. Photos by B. Lawhead, ABR, Inc. 

Copyright ConocoPhillips Alaska, Inc. 

32 
APPENDIX D. ANNOTATED BIBLIOGRAPHY 

Cameron, R. D., and K. R. Whitten. 1976. First interim report of the effects of the Trans-Alaska Pipeline on caribou movements. Special Report Number 2. Joint State/Federal Fish & Wildlife Advisory 

Team, Anchorage. 39 pp. 

Study Location/Herd: 

• Alaska; North Slope; Haul Road (Dalton Highway); Central Arctic Herd 

Dates of Study: 

• Study conducted between July 1974 and December 1975 

Pipeline Characteristics: 

• Not specified; Trans-Alaska Pipeline System (TAPS) construction began during this study in early 

August 1975 

Study Design: 

• Aerial surveys to determine distribution, productivity, and movements of herd 

• Behavioral observations related to pipeline crossing behavior were recorded during road surveys 

along the Haul Road 

• Inferred crossings from track observations near road 

Objectives: 

• Determine herd identity, general population size, productivity, and seasonal movements of caribou in 

the vicinity of the pipeline corridor 

• Identify segments of corridor featuring high use by caribou 

• Characterize crossing behavior of caribou encountering the Haul Road, pipeline, and constructionrelated activities 

• Assess effectiveness of special crossings to allow unrestricted caribou movements 

Only the last two objectives are addressed in this annotation 

Data Quantity: 

• 200 road crossings 

• After construction of pipeline began, 23 group crossings by 74 individual caribou were recorded 

(August-December) 

Analytical Methods: 

• Conducted aerial surveys and road surveys of TAPS corridor 

• Used descriptive statistics to compare caribou calf numbers near the road to away from the road 

• Compared road berm height at road crossing locations to berm heights available in the area 

• Collared and relocated caribou 

• Compared latitude and longitude of caribou groups using t-tests 

Results: 

• 77% of crossings were east-southeasterly 

. • 8 sag-bend crossings are proposed within study area and their effectiveness will be evaluated at the 

end of the 1976 construction season 

• Mean(+/- SD) be1m height at crossing sites was 1.43 +/- 0.59 m compared to 1.70 +/- 0.76 mat the 

measured road profile, a significant difference 

• Maximum crossing rates of the road and pipe/construction pads occurred during June-August and 

relative frequency of crossings decreased from north to south 

• Includes detailed appendix of all crossing attempts and includes observation date, location, whether 

observation was visual or from track, group composition, direction of travel, pipeline height at 

attempted crossing, and comments as to caribou behavior and activity prior to crossing attempt 

• High crossing rates during the summer corresponded to high insect rates, possibly reflecting a greater 

tendency for random movement and higher crossing probability 

• All caribou observed crossing the pipeline were single bulls 

• 16 crossings involving 1-15 caribou were inferred from tracks; cows and calves were present in at 

least 3 of these groups 

33 
• Bulls were seen standing in shade of pipeline and made repeated crossings beneath elevated pipe as 

low as 1.1 m during periods of high temperatures and low wind velocities 

• Several crossing attempts involved some milling, running, or group separation as animals approached 

the pipeline; only one set of tracks indicated caribou crossed without a disturbance reaction and these 

tracks followed those of a group that had previously crossed 

• 12 group deflections were recorded 

• Some caribou were diverted at least 1.5 km; 6 crossings appeared to involve selection for areas of 

higher pipe clearance 

• 1 bull was seen paralleling the pipeline and crossing a short section where no pipe was in place; track 

records indicated 2 similar crossings 

Conclusions: 

• Caribou tended to select crossing sites where road berms were lower 

• Authors avoid making generalizations regarding the behavioral response of caribou to the pipeline 

until further studies are complete 

• In general, at the time of this study, authors felt "free passage and movement" requirement was not 

being satisfied 

• Data in this report were intended to be baseline data; however, investigations were conducted during 

some of the early stages of pipeline construction 

Peer Reviewed: No 

Cameron, R. D., and K. R. Whitten. 1977. Second interim report of the effects of the Trans-Alaska Pipeline on caribou movements. Special Report Number 8. Joint State/Federal Fish & Wildlife Advisory 

Team, Anchorage. 34 pp. 

Study Location/Herd: 

• Alaska; North Slope; Central Arctic Herd 

Dates of Study: 

• Spring; calving; postcalving; insect period; fall; rut; March-November 1976 

Pipeline Characteristics: 

• Elevated, with some below-ground sections 

• Held on VSMs, spacing unspecified 

• Diameter 122 cm 

• Height 1-5 m above ground 

Study Design: 

• Recorded observations of crossing behavior during road surveys conducted along the Haul Road 

(Dalton Highway) 

• Track surveys 

Objectives: 

• Detennine herd identity, general population size, productivity, and seasonal movements of caribou in 

the vicinity of the pipeline corridor 

• Characterize crossing behavior of caribou encountering the Haul Road, pipeline, and constructionrelated activities 

• Assess effectiveness of special crossings to allow unrestricted caribou movements 

Only the last two objectives are addressed in this annotation 

Data Quantity: 

• 16 group crossings by 13 5 caribou 

Analytical Methods: 

• Conducted aerial surveys and road surveys of TAPS corridor 

• Used descriptive statistics to compare caribou calf numbers near the road to away from the road 

• Collared and relocated caribou 

Results: 

• Crossing rate of Haul Road by caribou was lower in 1976 than in 1975 

34 
• Fewer caribou were seen near the Haul Road in 197 6, and those present crossed less often compared 

to 1975 

• Contact of caribou with pipeline varied among seasons, with wide differences in snow cover, habitat, 

insect conditions, and construction-related activities 

• Includes detailed appendix of all crossing attempts and includes observation date, location, whether 

observation was visual or from tracks, group composition, direction of travel, pipeline height at 

attempted crossing, and comments on caribou behavior and activity before crossing attempt 

• 5 of 13 5 caribou that approached the pipeline were deflected from crossing 

• 11 groups totaling 110 caribou were observed, while remainder of crossing attempts were inferred 

from tracks 

• Of successful crossings by individual caribou, 80 were bulls, 3 were cows, and 1 was a short yearling 

• No crossings by cows with calves were apparent from tracks 

• Few caribou were seen near the pipeline during insect season, whereas the majority of crossings in 

197 5 occurred during that period 

• In 1976, most crossings of the pipeline were during late spring in an area where dust from Haul Road 

accelerated snow melt, exposing plants and stimulating early new growth of Eriophorum 

• Although many pipeline crossings in 1975 occurred during and after fall rut, only 2 crossings occurred during this period in 1976 

• Only one specially designated big game crossing (DBGC; consisting of higher-than-normal pipe 

elevation) was used for crossing 

• No observations of caribou using sag bends (other crossing structures) 

• Several crossing occurred in short sections where no pipeline was yet in place 

Conclusions: 

• Marked differences between 1975 and 1976 caribou interactions with the pipeline 

• Interpretation of results was difficult due to differences in length of pipe constructed and the amount 

of construction activity between years 

• Authors concluded that caribou generally avoided the corridor 

• Majority of crossings occurred where pipe was buried 

• Local traffic and human activity may have prevented caribou from crossing pipeline 

• Buried pipe did not seem to impede caribou movements in the absence of human activity 

Peer Reviewed: No 

Cameron, R. D., and K. R. Whitten. 1978. Third interim report of the effects of the Trans-Alaska Pipeline on caribou movements. Special Report Number 22. Joint State/Federal Fish & Wildlife Advisory 

Team, Anchorage. 29 pp. 

Study Location/Herd: 

• Alaska; North Slope; Haul Road (Dalton Highway); Central Arctic Herd 

Dates of Study: 

• Spring; summer; calving; postcalving, insect period; fall; rut; March-November 1977 

Pipeline Characteristics: 

• Trans-Alaska Pipeline north of Pump Station 4; dimensions of study area not specified 

Study Design: 

Crossings were inferred from.track surveys 

Objectives: 

• Determine herd identity, general population size, productivity, and seasonal movements of caribou in 

the vicinity of the TAPS corridor 

• Characterize crossing behavior of caribou encountering the Haul Road (Dalton Highway), pipeline, 

and construction-related activities 

• Assess effectiveness of special crossings to allow unrestricted caribou movements 

Only the last two objectives are addressed in this annotation 

35 
Data Quantity: 

• 11 group/single crossings as inferred from tracks 

Analytical Methods: 

• Conducted aerial surveys and road surveys of TAPS corridor 

• Used descriptive statistics to compare caribou calf numbers near the road to away from the road 

• Collared and relocated caribou 

Results: 

• Seasonal trends and sighting frequency of caribou near the road/pipeline corridor in 1977 were similar 

to 1976 

• Summer and fall sighting frequencies for both 1976 and 1977 were substantially lower than initial 

( 1975) values 

• Crossing frequencies of the corridor during all seasons were higher in 1977 than in 197 6 

• Whereas 1977 spring crossing frequency was near zero, summer rates were similar to 197 6 

• Crossing rates in fall 1977 were higher than in both fall 1975 and 1976 and may be related to a reduction in human activity along the corridor during this period 

• In 1977 fewer surveys specifically designed to detect caribou crossings of the pipeline/road corridor 

were conducted than in previous years 

• Includes detailed appendix of all crossing attempts and includes observation date, location, whether 

observation was visual or from track, group composition, direction of travel, pipeline height at 

attempted crossing, and comments as to caribou behavior and activity prior to crossing attempt 

• Tracks indicated use of a sag-bend crossing 

• Cows with calves appeared to avoid the corridor, so few observations of crossing attempts were seen, 

but there was little evidence that cows with calves were making unrestricted movements across the 

pipeline corridor 

Conclusions: 

• Infrequent use of the pipeline/road corridor continues to limit conclusions about effectiveness of 

crossing structures 

• Factors influencing behavioral responses of cows with calves should receive priority attention 

• In the absence of human activity, buried pipe allowed caribou to freely cross the pipeline 

• Vehicles and other human activities along the corridor represent a greater source of disturbance to 

caribou than do structures 

• Excessive berm height may prevent caribou from crossing Haul Road 

• Free passage and movement of caribou across the road/pipeline corridor cannot be demonstrated with 

this study 

Peer Reviewed: No 

Carruthers, D.R., and R. D. Jakimchuk. 1987. Migratory movements of the Nelchina caribou herd in 

relation to the Trans-Alaska Pipeline. Wildlife Society Bulletin 15: 414-420. 

Study Location/Herd: 

• Southcentral Alaska; Trans-Alaska Pipeline System (TAPS) miles 620-660; Nelchina Herd (see Carruthers et al. 1984 for more extensive description of study area and background information on the 

Nelchina Herd) 

Dates of Study: 

• October; November; April; fall; spring; 1981-1983 

Pipeline Characteristics: 

36 

• Trans-Alaska Pipeline 

• Elevated to average height of2.4 m above ground; 92.6% oflength > 1.8 min height 

• Pipe diameter 122 cm 

• VSMs spaced at 18-m intervals 

• Crossing structures included sections of buried pipe, specially designated big-game crossings 

(DBGCs), and sag-bends (short sections of buried pipe) 
• Buried sections ranged in length from 2.4 to 3.2 km wide, comprising 39% of pipeline length in study 

area 

• 30 elevated underpasses, designated big game crossings (SBGC); average height >3.3 m and 18 m 

long 

• 6 sag-bends; all <18 m wide 

• Right of way (ROW) averaged 30 m wide, including 7-m-wide gravel pad about 1 m thick 

Study Design: 

• Track surveys with pipe mode and height, snow depth, and vegetation type recorded at each trail 

• See report by Carruthers et al. 1984 for presentation of same data 

Objectives: 

• Describe crossing locations of caribou in relation to characteristics of the pipeline and surrounding 

environment 

• Compare crossing locations of the herd after pipeline construction with crossing locations before 

pipeline construction 

Data Quantity: 

• 11 surveys by truck or snowmachine over the course of 3 years 

• Estimated 7,909 caribou on pipeline right-of-way 

Analytical Methods: 

• Chi-square goodness-of-fit tests of habitat use and use of buried pipe sections, by area and season 

Results: 

• Estimated 7,909 caribou on pipeline right-of-way, with all but 4 crossing the pipeline 

• Spring crossing zones were associated with lowlands, whereas fall crossing zones were associated 

with hilly terrain and mixed woodland forest; vegetation types at specific crossing sites did not differ 

statistically from the availability of vegetation within crossing zones 

• Continuity of pipeline mode was consistent over long distances, so caribou were rarely presented with 

a choice of pipe mode, but in some sections, caribou showed preference for above-ground elevated 

pipe in spring and buried pipe in fall, whereas there was no relationship in other areas 

• Mean pipeline height at crossing sites was 2.5 m, compared with a mean availability of2.3 m, within 

spring and fall crossing zones 

• Elevated sections >3 m high and sag-bends received little use 

• Caribou used the same migration routes before and after pipeline construction 

• See Carruthers et al. (1984) for full report on this study 

Conclusions: 

• Crossing zones were associated with physiographic features distinctive for each season 

• Pipe mode and height did not appear to influence the location of crossing zones, but in sections where 

a choice was available, there was much variability 

• Caribou tended to cross at whatever pipe mode or height they encountered, so unless special crossing 

structures were within the migratory corridor of the herd, they may not have been used 

Peer Reviewed: Yes 

Carruthers, D.R., R. D. Jakimchuk, and C. Linkswiler. 1984. Spring and fall movements of Nelchina 

caribou in relation to the Trans-Alaska Pipeline. Final report prepared for Alyeska Pipeline Service 

Company, Anchorage, by Renewable Resources Consulting Services Ltd. 102 pp. 

Study Location/Herd: 

• Southcentral Alaska; Trans-Alaska Pipeline System (TAPS) miles 620-660; Nelchina Herd 

Dates of Study: 

• October; November; April; migration; fall; spring; 1981-1983 

Pipeline Characteristics: 

• Trans-Alaska Pipeline 

• Elevated, average height 2.4 m above ground; 92.6% of length > 1.8 m in height 

• Pipe diameter 122 cm 

37 
• VSMs spaced at 18-m intervals 

• Crossing structures included sections of buried pipe, specially designated big-game crossings 

(DBGCs), and sag-bends (short sections of buried pipe) 

• Buried sections ranged in length from 2.4 to 3.2 km wide, constituting 39% of pipeline length in 

study area 

• 30 elevated underpasses, designated big game crossings (DBGCs); average height >3.3 m and 18 m 

long 

• 6 sag-bends; all <18 m wide 

• Right-of-way (ROW) averaged 30 m wide, including a 7-m-wide gravel pad, about 1 m thick 

Study Design: 

11 track surveys over the course of 3 years by truck or snowmachine and 213 hours of direct observation during 1981 

• Every third set of tracks was measured to determine their configuration within 20 m (200 m during 

1981) of TAPS ROW 

• Only tracks that could be followed across the corridor were characterized, which may have biased 

results toward direct crossings of pipeline 

• Successful crossing was defined as any caribou that approached the pipe and moved across to the 

other side 

• Pipe mode and height at point of crossing was measured and compared with "as-built" pipeline specifications 

• Vegetation was classified and snow depth was measured at crossing sites 

• Six control surveys were conducted in areas of high caribou use; walked transect parallel to ROW and 

500 m away and series of 250 m transects perpendicular to pipeline 

Objectives: 

• Document crossings of TAPS corridor by N elchina Herd during spring and fall migration 

• Document and describe physical characteristics of pipeline crossing sites used by caribou 

• Assess use of special crossing structures by caribou 

• Quantify crossing success and behavior of caribou encountering pipeline corridor 

• Document group characteristics that may affect crossing success 

• Document habitat use by caribou adjacent to the pipeline corridor 

Data Quantity: 

• Estimated 7,909 caribou on pipeline right-of-way from track surveys 

• 122 groups comprising 880 caribou were observed crossing TAPS ROW 

Analytical Methods: 

• Compared use of buried pipelines to availability with a chi-square test 

• Descriptive statistics of pipeline height 

• Described caribou activity on TAPS right-of-way 

Results: 

38 

• Seasonal movements were described, but are not summarized in this annotation 

• Of 122 caribou groups observed crossing ROW, 105 (86%) crossed at buried pipe and 17 ( 14%) at 

above-ground pipe 

• In spring, 66% of caribou crossed under a 20-km section, and during fall, 80% of caribou crossed 

under a 20-km section 

• Topographic features of spring and fall crossing sites differed, with spring sites occupying depressed 

flat terrain adjacent to uplands, whereas fall crossing sites were associated with uplands and sloped 

topography 

• Trails were not associated with particular vegetation types, but reflected topographic differences between seasonal migrations 

• No relationship between forage quality and the frequency of caribou crossings was found 

• Maximum snow depths during study were normal or below normal except November 1981 to January 

1982, when snow depth exceeded normal by 10-20 cm; considered doubtful that snow depths would 

restrict caribou movements during spring or fall 
• Snow depths during 1981-1983 were 32% lower on TAPS ROW than in adjacent areas 

• Snow depth at major spring crossing sites was low (<44 cm) and was intermediate (range 25-38 cm) 

at fall crossing sites 

• Spring migration corridors were located in sections of TAPS with high proportion (76%) of aboveground pipe 

• Fall migration corridors were in areas where most of pipe (65%) was buried 

• Only one section of pipeline presented caribou with a choice of pipe mode, and no selection was evident for elevated or buried pipe 

• Distribution of pipe heights did not differ between spring and fall crossing zones 

• Most pipe at crossing sites was > 1.8 m, with height ranging from 1.0 to 5 .1 m 

• Median pipe height at sites crossed in spring and fall was 2.3 m and mean height crossed by caribou 

was 2.5 m 

• Presence of predators in the ROW was discussed, but is not presented in this annotation 

• 29% of caribou used some sort of special crossing structure (pipeline burial, DBGCs, sag-bends) 

• Buried sections were used most (27% of crossings) because they were situated in a major spring 

crossing zone; all other structures were used little, probably because they were placed outside of major crossing zones 

• All structures were used less in fall than spring 

• Of estimated 7,905 caribou approaching pipeline, all trails but one crossed; 49% of trails crossed at 

above-ground pipe 

• All 149 caribou groups observed directly during spring and fall 1981 crossed TAPS 

• At above-ground pipe, there was a significant change in travel direction ( ~ 7 .2 degrees) where caribou 

crossed TAPS compared with areas away from TAPS 

• In 92% of crossings, caribou crossed ROW directly with <25 m of lateral movement, but some trails 

paralleled 25 m from pipeline, approached or departed the pipe on old cutlines, or encountered a transition between above-ground and buried pipe 

• No differences were seen in approach and departure orientations between pipe modes 

• Paralleling elevated pipe during approach occurred on ROW during 2 (7%) trials for an average of 

51 m; occurred off ROW during 5 (17%) for average of 88 m 

• Paralleling elevated pipe during departure occurred on ROW during 9 (30%) trials for average of 111 

m compared to 5 ( 17%) trials over average of 52 m at buried pipe 

• At 17 (35%) of above-ground crossing sites, a cutline intersected and crossed ROW at 90 degrees 

with caribou encountering cutline off ROW and following it directly across pipeline 

• Visibility of ROW varied depending on forest type, but visibility declined rapidly >50 m from ROW 

and was seldom visible to researchers beyond 125 m 

• No relationship was found between angle of caribou trails relative to TAPS for either elevated pipe or 

buried pipe 

• All 122 groups directly observed from October to November crossed TAPS; 14% at elevated pipe and 

86% at buried pipe 

• Regardless of pipe mode, groups spent average of 7.6 minutes on ROW before departing, with small 

groups generally spending less time on ROW than large groups 

• 92% of 59 groups were led by adult females, 5% of groups were led by bulls, 3% were led by calves 

• Although not significant, caribou spent more time feeding (44%) and less time standing (28%) at 

elevated pipe than at buried pipe (20% and 38%, respectively) 

• Proportions of different caribou groups observed at elevated and buried pipe did not differ significantly 

• 91 caribou in 15 groups showed alarm behavior, including 4 groups at elevated pipe and 11 at buried 

pipe 

Conclusions: 

• Caribou followed traditional migratory corridors and seldom used special crossing structures, probably because they were located outside of major migratory corridors 

• Where both pipe modes were available, there was no preference for buried or elevated pipe 

39 
• Distribution of height along TAPS was so uniform that no analysis could be made to test for selection 

of height at crossing sites 

• Caribou often crossed at median pipe height 

• Caribou tended to cross elevated pipe where they encountered it 

• Factors other than pipe height are likely to influence where caribou cross elevated pipe, with the foremost being topography 

• Conclusions on preferences for crossing sites depend on what components researchers decide are 

available to animals 

• Inconclusive nature of studies regarding selection of pipe height at crossing sites of moose and caribou reinforce the hypothesis that factors other than height are important 

Authors list management recommendations: 

• Study caribou movements over long periods of time, taking into account changes in population status, 

and determine where major caribou movements will intersect proposed pipelines 

• Route selection should be aimed at allowing pipe burial at crossings or elevated pipes within height 

ranges presented in this report 

• Snow conditions along route should be analyzed to ensure that adequate pipe heights for crossing will 

be available during winter -

• Hunting should not be allowed near pipelines 

• Specially designated big game crossings and sag-bends were not necessary to enable successful crossings of pipeline by caribou 

Peer Reviewed: No 

Child, K. N. 1973. Reactions of barren-ground caribou (Rangifer tarandus granti) to simulated pipelines 

and pipeline crossing structures at Prudhoe Bay, Alaska. Report prepared for Alyeska Pipeline Service 

Company and British Petroleum Alaska, Inc., Anchorage, by Alaska Cooperative Wildlife Research 

Unit, University of Alaska, Fairbanks. 51 pp. 

Study Location/Herd: 

• Alaska; North Slope: coastal plain; Prudhoe Bay; Central Arctic Herd 

Dates of Study: 

• Summer; no dates specified; 1971 and 1972 

Pipeline Characteristics: 

First simulation by Alyeska Pipeline Service Company 

• Simulated elevated pipeline made of snow fencing with burlap stapled to one side to form an optical 

baffier similar to a real pipeline 

• Height of snow fencing was 4 ft to simulate a 48-in.-diameter pipeline 

• Height 20 in. above ground 

• VSMs were sprnce poles spaced at 25-ft intervals 

• Length 10,200 ft 

• Crossing structures included 2 gravel ramps and 4 underpasses 

• Ramps 7 5 and l 00 ft in length, 2: 1 side slopes, aligned with axis of fence 

• 3 underpasses were 100 ft long and 7 ft 8 in. high, 1 underpass was 150 ft long and 4 ft high; all underpasses were constructed with 2 parallel spans of fencing 

• Design changed during 1972 (second year of study), ramps were reconstructed to be equal in length 

with 1 :5 slopes that fanned out 360 degrees from fence; 3 of 4 underpasses were increased in length 

to 200 ft; and at 2 of 4 underpasses, burlap/fencing were replaced by 32-in. galvanized culverts to 

remove disturbing stimulus of burlap blowing in wind 

• Baffier constructed to prevent caribou from walking around simulation and to help funnel caribou 

into the pipeline area 

Second simulation by British Petroleum Alaska, Inc. (BP Alaska) 

40 

• Simulated elevated feeder pipeline, 3,600 ft long, made of culverts suspended on water-filled oil 

drums, height not specified 
• 24-in. diameter 

• 600 ft of pipeline was raised to provide a variety of ground clearances ( 4-8 ft) 

• Expansion loop simulated, dimensions 20 by 40 ft, eastward inclination of loop had 6- and 8- ft clearances above the road and tundra, respectively 

• Included structures to channel caribou towards the simulated pipeline 

• In 1972, lengthened the simulation another 3,500 ft and adding 2 ramps as crossing structures, also 

used 10-in.-diameter spruce logs instead of culverts 

• Ramps were 2,000 ft apart, each with 1: 10 slopes; length of ramps unspecified; structure included 

100-ft cable leads positioned 45 degrees to axis ofroad bed to intercept and lead caribou over ramps 

Study Design: 

• Behavioral observations conducted from 14-ft-high towers; 1 tower at each simulation 

• Crossing defined as successful when animal negotiated structures at a ramp or underpass, or crawled 

under pipeline; groups of caribou were considered successful when 100% of the group crossed the 

pipeline simulation 

Objectives: 

• Study behavior of animals by sex and age and by size and composition in the vicinity of man-made 

objects 

• Study reactions of caribou when presented with deflection or choice situations 

• Study reactions of maternal cows and calves when confronting man-made structures 

Data Quantity: 

• 5,599 caribou approachedAlyeska's simulated pipeline structure in 1971 and 1972 

• 1,362 caribou approached BP's simulated pipeline structure in 1971 and 1972 

Analytical Methods: 

• Crossing success and group size were compared using chi-square tests 

• Crossing success was compared by insect activity, elapsed time, and number of encounters with pipeline (but not pipeline height) using multiple linear regression 

• Numbers of caribou using ramps and underpasses presented using descriptive statistics 

Results: 

• Groups and individuals encountering the pipeline tended to parallel at an average distance of 50 m 

• Of 5,599 caribou approaching Alyeska simulation, 994 (17.6%) used ramps; 273 (4.9%) used underpasses; 36 (0.7%) crossed beneath the fence; 1,924 (34.4%) reversed original direction of travel at the 

pipeline; 2,372 (42.4%) moved to termini of structure 

• Of 1,362 caribou approaching BP feeder pipeline simulation, 92 (6.8%) passed beneath the pipe; 

113 (8.3%) used low-profile ramps; 129 (9.5%) reversed their movements; 1,028 (75.4%) moved to 

termini of structure 

• As group size increased, crossing success decreased, with 27 (24.5%) of 110 groups crossing the Alyeska simulation using ramps and underpasses, whereas 83 groups (75.5%) did not use either structure 

to cross 

• Groups of 2-10 were more likely to investigate and use ramps (12.9%) than were larger groups (7.5%) 

• Larger groups did not negotiate crossings as entire group; rather, they moved to termini of structure, 

reversed travel direction, or separated into subgroups before crossing at various locations 

• 21 (69.0%) of 34 individual animals that approached pipeline used ramps or underpasses to cross 

• Groups of adult bulls or mixed herds with high numbers of bulls frequently bypassed all crossing 

structures and paralleled the simulation to termini 

• Nursery bands mostly paralleled the structure or reversed direction of travel (especially large groups), 

but remained longer in vicinity of the pipeline and investigated crossing structures, using them more 

often than bull groups 

• 3 of 23 groups (35%) that separated to cross the pipeline reunited on the other side; in 3 instances, 

distinct groups approaching simultaneously coalesced; typically, inter- and intra-group dynamics 

maintained some synchrony of activities between different groups attempting to cross, usually resulting in caribou moving to termini of structures 

41 
• Groups led by females used ramps to cross pipelines significantly more often than groups led by bulls, 

which tended to avoid structures by making wide detours to termini of structures 

• Crossing success of caribou was significantly correlated with increasing densities of insects, number 

of occasions when animals were present at the simulations, and time of season 

• Multiple regression analysis showed density of biting insects to be the one environmental factor that 

greatly influenced crossing success 

• During both years, caribou that successfully crossed Alyeska simulation used ramps more frequently 

than elevated underpasses, which were avoided 

• Of 42 cow-calf pairs seen encountering the simulation, 23 pairs successfully crossed 

• Although calves tended to be more inquisitive than adults, they never initiated crossings, but followed 

their dams 

Conclusions: 

Author made management recommendations: 

• Use aerial photos to identify and map traditional trail systems used by caribou and to identify areas of 

potential conflict 

• 3 or more crossing structures should be included equidistant from each other in areas where pipelines 

intersect caribou trails 

• Crossing structures should be as wide as possible to give caribou the maximum chance to find the 

structure and to provide for the passage of large groups 

• Above-ground pipelines should be elevated to a minimum ground clearance to minimize the visual 

barrier presented to caribou 

• Crossing structures should be situated along terrain features followed by caribou such as river channels, edges of lakes, and ridges of polygons 

• If building a crossing structure is not feasible, pipelines should not be <50 yards from waterbodies to 

reduce the chances of confinement between waterbody and the pipeline 

• A discontinuous pipeline profile created by building as many crossing facilities as possible may encourage caribou to investigate the structure 

• Gravel ramps should be constructed with maximum width and slopes not exceeding 1 :6; more work 

should be done to study the effectiveness of lead fences to channeling caribou towards crossing structures; leads should be made of stationary material so wind cannot cause movement 

• Simulating trails over ramps may facilitate use; during winter, black powder could be spread over the 

ramp to look like a trail, snowmachines could be used to put in a trail, or planks could be placed along 

ramps to funnel caribou over them 

• Vegetated ramps are feasible, but impractical due to maintenance costs and the possibility of attracting stationary groups of caribou 

• Further research is needed regarding accumulation of snow around features and whether or not a seasonal response of caribou to pipelines may occur 

Peer Reviewed: 

Child, K. N. 1974. Reaction of caribou to various types of simulated pipelines at Prudhoe Bay, Alaska. 

Pages 805-812 in V. Geist and F. Walther, editors. The Behaviour of Ungulates and Its Relation to Management. IUCN New Series Publications No. 24, Volume II. Morges, Switzerland. 940 pp. 

Study Location/Herd: 

• Alaska; North Slope: coastal plain; Prudhoe Bay; Central Arctic Herd 

Dates of Study: 

• Calving; postcalving; insect season; 8 June to 8 August 1971 

Pipeline Characteristics: 

First simulation by Alyeska Pipeline Service Company 

42 

• Simulated elevated pipeline made of snow fencing with burlap stapled to one side to form an optical 

barrier similar to a real pipeline 

• Width of snow fencing 4 ft to simulate a 48-in. diameter pipeline 
• Height 20 in. above ground 

• VSMs were spruce poles spaced at 25-ft intervals 

• Length 10,200 ft 

• Crossing structures included 2 gravel ramps and 4 underpasses 

• Ramps 75 and 100 ft in length, 2:1 side slopes, aligned with axis offence 

• 3 underpasses were 100 ft long and 7 ft 8 in high, 1 underpass was 150 ft long and 4 ft high; all underpasses were constructed with 2 parallel spans of fencing 

Second simulation by British Petroleum Alaska, Inc. (BP Alaska) 

• Simulated elevated pipeline, 3600 ft long 

• Culverts suspended on water-filled oil drums, 30 in. high 

• 24-in. diameter 

• 600 ft of pipeline was raised to provide a variety of ground clearances ( 4-8 ft) 

• Expansion loop simulated, dimensions 20 by 40 ft, eastward inclination of loop had 6- and 8-ft clearances above the work-pad road and tundra, respectively 

• Included structures to channel caribou toward the simulated pipeline 

Study Design: 

• Behavioral observations conducted from 14-ft-high towers; 1 tower at each simulation 

• 16-mm cinematography used to record some behavioral sequences 

• Crossing defined as successful when animal negotiated structures at a ramp, underpass, or crawled 

under pipeline; Groups of caribou where considered successful when 100% of the group crossed the 

pipeline simulation 

Objectives: 

• Study behavior of animals by sex and age and by size and composition in the vicinity of man-made 

objects 

• Study reactions of caribou when.presented with deflection or choice situations 

• Study reactions of maternal cows and calves when confronting man-made structures 

Data Quantity: 

• 1,102 caribou encounters at Alyeska site (including 186 track counts) 

• 605 caribou encounters at BP site 

Analytical Methods: 

• Descriptive statistics only 

Results: 

• AtAlyeska simulation, 136 (12.4%) caribou used ramps, 60 (5.4%) walked through underpasses, 7 

(0.6%) crawled under the fencing, and 899 (81.6%) were diverted in their movements 

• At BP simulation, I 01 (16.7%) reversed direction of travel, 495 (81.8%) paralleled the line to the 

terminus, and 9 ( 1.5%) crawled underneath 

• On basis of 301 animals approaching Alyeska simulation from east, 42.5% of caribou used crossing 

structures, 43.2% moved to termini, and 13.6% returned to east; whereas 801 approaches from west 

resulted in 8.4% using ramps and underpasses, 19% moved to termini, and 71.8% returned to west 

• At BP simulation, of 51 caribou moving east, 7.8% crossed the pipeline and 92.2% diverted to ends of 

simulation; of 554 approaches from west, 0.9% of caribou crawled beneath the pipe, 80.9% moved to 

termini, and 18.2% returned to east 

• Greater proportion of cows, calves, and yearling caribou used ramps than used underpasses 

• At Alyeska simulation, groups of 11-15 animals made greater use of ramps and underpasses than did 

larger groups 

• Even though small groups usually paralleled the simulation, groups of 6-10 were more inclined to 

investigate potential crossing structures than were larger groups 

• 83% of all animals that encountered the Alyeska simulation were diverted from their original course; 

smaller groups traveled to termini whereas larger groups reversed their direction of travel 

Conclusions: 

• Responses of caribou groups and individuals to simulated pipelines differed according to sex, ageclass, group size, and group composition 

43 
• Caribou usually paralleled structures for some distance before returning to their points of origin or 

eventually seeking access to the other side at the terminus of the simulation 

• More study is needed to determine if caribou can learn to use ramps and overpasses, and whether 

caribou vary in response to pipelines depending on season 

• Author felt results were inconclusive and planned to address further concerns during 1972 field season (see Child 1973) 

Peer Reviewed: Yes 

Child, K. N. 1975. A specific problem: The reaction of reindeer and caribou to pipelines. Pages 14-32 in 

J. R. Luick, P.C. Lent, D.R. Klein, and R.G. White, editors. Proceedings of the First International Reindeer/Caribou Symposium. 9-11 August 1972, Fairbanks, Alaska. University of Alaska, Fairbanks. 

Study Location/Herd: 

• Alaska; North Slope; Arctic Coastal Plain; Seward Peninsula 

Dates of Study: 

• Summer 1971, 1972 

Pipeline Characteristics: 

First study at Prudhoe Bay: 

• Simulated elevated pipeline 

• Height 0.6 m above ground 

• Diameter 1.2 m 

• Crossing structures included ramps (buried pipeline) 21 m and 100 min width, height 2.4 mat vertical supports, and 1 :2 slope 

• Two low-profile ramps with 1:10 slopes located 610 m from each other 

• Three underpasses 31 m wide and 2.4 m high 

• One underpass 46 m wide and 1.2 m high 

• Simulated elevated feeder pipeline with height 0.7 m above ground with underpasses as crossing 

structures, 0.9 m and 2.4 min height 

Second study on Seward Peninsula: 

• Simulated elevated pipeline 

• Diameter 0.8 m 

• Height unspecified 

• Crossing structures included a gravel ramp with I :4 side slope and underpass 61 m in height 

Study Design: 

• Not described 

Objectives: 

• Determine whether or not caribou would adapt to the presence of pipeline structures and successfully 

cross them; to study the behavioral responses of caribou to simulated pipeline structures 

Data Quantity: 

• Not included in paper 

Analytical Methods: 

• Not included in paper 

Results: 

• Not included in paper 

Conclusions: 

• Not included in paper 

Peer Reviewed: Yes 

Child, K. N., and P. C. Lent. 1973. The reactions of reindeer to a pipeline simulation at Penny River, 

Alaska. Interim report by Alaska Cooperative Wildlife Research Unit, University of Alaska, Fairbanks. 

29 pp. 

44 
Study Location/Herd: 

• Alaska; Seward Peninsula; semi-domesticated reindeer 

Dates of Study: 

• Winter; spring; summer; fall; pre-calving; post-calving; insect period; rut 

Pipeline Characteristics: 

• Simulated elevated pipeline, 24 in. high 

• 32-in. diameter 

• Vertical supports spaced at 10-ft intervals 

• Crossing structures included a gravel ramp 116 ft long, 66 ft wide, 8 ft maximal height, 1:3 slope 

• Immediately adjacent to ramp was an arching underpass, 323 ft long with a maximum of 12 ft and 

minimum of 6 ft ground clearance 

Study Design: 

• Behavioral observations with binoculars and 16-mm cinematography 

• Reindeer were herded into area either by snowmachines or herders on foot 

Objectives: 

• Evaluate seasonal responses of reindeer to the pipeline 

• Evaluate changes in mother-infant behavior or sex-/age-related responses associated with the pipeline 

Data Quantity: 

• Not specified 

Analytical Methods: 

• Behavioral descriptions 

Results: 

• Pipeline approach distance was ~50 m, but near overpass, this distance increased to 125 m, suggesting 

increased visual disturbance by the higher structure 

• Reindeer crossed pipeline when snow formed bridges over pipeline and when under severe insect 

harassment 

• Little behavioral information on cow-calf pairs acquired; gathered on 2 occasions when a cow was 

separated by the pipeline from her calf and neither attempted to cross the pipeline to reunite 

• Reindeer avoided the pipeline even after long periods of undisturbed investigation and were reluctant 

to cross even when herded by snowmachine or people on foot 

• Group reactions to the pipeline seemed to depend on the behavior of a few individuals directly adjacent to pipeline 

Conclusions: 

• During all seasons, reindeer displayed general avoidance of the pipeline, frequently moving parallel 

to structure and crossing at the structure's termini 

• Failure to use crossing structures may have been due to unfamiliarity, lack of motivation to cross, 

optical complexity of overpass, visual contrast between snow and dark pipeline, or audible noises 

emanating from pipeline supports 

• Authors list several suggestions for improvement of future studies with simulated pipelines 

Peer Reviewed: No 

Coltrane, J. A., and R. B. Lanctot. 2001. The effect of vibration dampers on caribou (Rangifer tarandus) 

crossing success rate under the elevated Badami Pipeline, Alaska, 1999. Final report prepared for BP 

Exploration (Alaska) Inc., Anchorage, by LGLAlaska Research Associates, Inc., Anchorage. 20 pp. 

Study Location/Herd: 

• Alaska; North Slope; Prudhoe Bay oilfield; Central Arctic Herd 

Dates of Study: 

• Summer; postcalving; jnsect period; 24 June to 26 July 1999 

Pipeline Characteristics: 

• Badami Pipeline, elevated to minimum of 1.5 m above tundra. except for 3 areas of lower pipe totaling 600 linear ft 

45 
• No road associated with pipeline 

• 40 km long 

• Pipeline vibration dampeners (PVDs) hung along 4 sections, or 8,284 m (2 l % of total pipeline length) 

• 2 PVDs placed between each pair ofVSMs; one at 1/2 span, or 8.4 m from VSM, and other at 1/4 

span, or 4.3 m from VSM 

• PVDs hang 51 cm below pipeline 

Study Design: 

Behavioral observations conducted from 2 towers between 0930 and 2230 Alaska Daylight Savings 

Time 

• Observations from 6 time-lapse video cameras taking pictures at 6-8 second intervals set up at pipeline sections that were buried, and at pipeline sections with and without PVDs 

• Sampled insect abundance and also calculated insect activity index from data collected at weather stations 

• Criteria used to judge a successful group crossing was not specified 

• Caribou observed within a 500 m approach zone were classified as intending to cross pipeline 

Objectives: 

• Quantify and compare crossing success of caribou along the Badami pipeline at sections with and 

without PVDs 

• Determine if group size, composition, and insect activity affected caribou crossing success and behavior 

Data Quantity: 

• 94 caribou groups comprising 3,474 individuals observed from towers 

• For total caribou observed with cameras, see results below 

Analytical Methods: 

• Compared caribou crossing success h1 one area with PVDs and one area without PVDs 

• Compared crossing success of groups using chi-square tests of independence 

• Compared percentage of group crossing using analysis of variance (ANOVA) 

• Compared crossing success of group-size categories using chi-square test of independence 

Results: 

• 37% of caribou near pipelines with PVDs crossed, compared with 58% of groups near pipelines without PVDs; difference was not significant 

• Crossing success of individual caribou was significantly different between sites with and without 

PVDs; 27% of caribou near pipelines with PVDs crossed, compared with 63% near pipelines without 

PVDs 

• No significant difference in average group size of caribou near pipelines with PVDs and without 

PVDs 

• No significant difference in sex and age class of caribou near pipelines with PVDs and without PVDs 

• No significant effect of group size on crossing success at all pipeline configurations combined 

• No significant effect of group type on crossing success at all pipeline configurations combined 

• Mosquitoes present on 12 sampling days and absent on 14 days; oestrid flies considered to be present 

for only 4 hr over 2 days 

• For both pipeline configurations, mosquito presence significantly decreased likelihood of caribou 

crossing all pipeline configurations combined, and for sections with PVDs 

• Mosquito presence had no significant effect on crossing success at sites without PVDs 

• During camera monitoring, mosquitoes were present on 12 days and absent on 23 days; oestrid flies 

present on only 2 days 

• 813 caribou recorded crossing sections of pipeline with PVDs 

• 639 caribou recorded crossing sections of pipeline without PVDs 

• 1,034 caribou recorded crossing sections of buried pipeline at river site 

Conclusions: 

46 

• Based on tower observations, caribou may have been less likely to cross Badami Pipeline where 

PVDs are present 
i 

I 

I 

I 

I 

I 

I 

I 

I 

Authors felt flaws in study design may have biased their results 

One plot with PVDs was located near the Sagavanirktok River and caribou may have been traveling 

through the river corridor on way to coast with no intention of crossing the pipeline located in the plot 

Another plot was located near the Endicott Pipeline and road; vehicle traffic on road may have funneled caribou into study area or altered crossing frequencies 

Cameras were only useful in recording whether caribou crossed the pipeline, but viewing angle was 

not large enough and pictures were not recorded frequently enough to quantify crossing success 

May have incorrectly assumed that caribou approaching within 500 m of pipeline intended to cross it; 

smaller approach zones would increase crossing success estimates 

This study suggested that group size and group type did not influence whether or not caribou crossed 

pipelines with and without PVDs 

Recommendations for future study included gathering paired observations of caribou in similar 

stretches of pipeline and habitats both with and without PVDs; cameras should be located at paired 

sites, with measurements focusing on magnitude of animals crossing, not evaluating crossing success; 

crossing success should be compared at same sites before and after installation of PVDs 

Peer Reviewed: No 

Cronin, M.A., W. B. Ballard, J. Truett, and R. Pollard. 1994. Mitigation of the effects of oil field development and transportation corridors on caribou. Final report to the Alaska Caribou Steering Committee prepared for Alaska Oil and Gas Association, U.S. Fish and Wildlife Service, Alaska Department of 

Fish and Game, and North Slope Borough, by LGL Alaska Research Associates, Inc., Anchorage. 113 

pp. 

Study Location/Herd: 

• Alaska; North Slope; Prudhoe Bay; Milne Point; Endicott, Kuparuk; Central Arctic Herd; Teshekpuk 

Lake Herd; Porcupine Herd; Nelchina Herd 

Dates of Study: 

• Various dates, studies conducted within Prudhoe Bay and along the Trans-Alaska Pipeline since 1970 

Pipeline Characteristics: 

• Various designs 

Study Design: 

• Literature review of published and unpublished reports and available unpublished data sets concerning the effects of oilfield development on caribou of the North Slope 

Objectives: 

Assess the impacts of oilfield development on caribou at the population and individual level 

Identify important types of mitigation measures for caribou in arctic Alaska 

• Identify mitigation measures for which effectiveness has not been clearly shown or adequately evaluated 

• Identify other mitigation measures that warrant consideration 

• Make recommendations for future studies of possible mitigation measures 

Data Quantity: 

• 160 publications were reviewed 

Analytical Methods: 

• Literature review with some reanalysis of previous data (Kuparuk and Endicott pipeline height selection) 

Results: 

Measures to mitigate the impact of pipelines on caribou passage include elevated and buried pipelines, separation of roads from pipelines, construction of gravel crossing ramps, and regulation of 

vehicle and foot traffic 

Elevated pipelines with minimum heights of 1.5 m (5 ft) have been effective in facilitating the movements of caribou, although heights> 1.5 m (5 ft) may be preferred by caribou 

At heights of at least 2.1 m (6.9 ft) above ground, the Trans-Alaska Pipeline allows passage of the 

Nelchina Herd 47 
• Crossing success of caribou encountering elevated pipelines was reduced where pipelines were located near (25-50 m) roads with high traffic rates (15 or more vehicles/hr); studies showed crossing 

success in these areas was ~50% lower than in reference areas 

• Separation of roads and pipelines to recommended distance of at least 152 m (500 feet) decreased 

possibility of forming a barrier to caribou movements 

• Roads without adjacent pipelines and with moderate traffic levels ( <15 vehicles/hr) may not be significant barriers 

• Effects of caribou group size on crossing success were variable among studies 

• No conclusive evidence was found to indicate that ramps facilitate crossings of pipelines elevated at 

least 1.5 m or reduce time spent by caribou adjacent to pipelines; unclear whether ramps are used opportunistically or whether caribou prefer them as crossing sites 

• Effectiveness of ramps may be improved by extending structures away from pipeline (because short 

ramps are likely to be missed by caribou) and by using low-grade slopes on all sides of ramps 

• No systematic studies of effectiveness oflong buried sections of pipeline had been done on the North 

Slope, but buried sections of the Trans-Alaska Pipeline were effective crossing structures for the 

Nelchina Herd 

• Extended burial of pipelines along road beds may be an effective mitigation measure 

• No evidence was found regarding the effectiveness of crossing structures in facilitating movements of 

nursery bands 

• Habituation to pipeline structures may occur 

Conclusions: 

• Elevate all pipes at least 1.5 m ( 5 ft) above ground level 

• Buried pipeline may be an effective alternative, but must consider cost, maintenance, suitability of 

substrate, and loss of wetlands 

• Limit number of roads on calving areas 

• Separate pipelines from roads by at least 152 m (500 ft) 

• Where large groups of caribou cross pipelines, use elevated pipe with road-pipe separation, buried 

pipe, or possibly ramps 

• Regulate vehicle traffic when caribou are moving through oilfields 

• Other mitigation measures may include employing personnel in oilfields to observe interactions with 

caribou and enforce regulations, prohibit unauthorized public access and hunting from roads within 

oilfields, maintain fixed-wing aircraft flight altitudes of 2:457 m (1500 ft) 

• Recommendations for future studies were provided 

Peer Reviewed: Yes (steering committee) 

Curatolo, J. A. 1983. Caribou movements, behavior, and interactions with oil-field development. A 

synthesis of pertinent research and unpublished 1982 field work in the Eileen West End, Kuparuk Oil 

Field, Alaska. Final report prepared for Sohio Alaska Petroleum Company, Anchorage, by Alaska Biological Research, Fairbanks. 74 pp. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• Various studies, late 1970s to early 1980s 

Pipeline Characteristics: 

• Trans-Alaska Pipeline 

• Kuparuk pipeline 

• Pipeline characteristics not specified 

Study Design: 

• Literature review 

48 
Objectives: 

• Describe caribou movements and use of Eileen West End area (western Prudhoe Bay oilfield) during 

calving/postcalving, mosquito season, and oestrid fly season 

• Describe effects of roads, pipelines, drill rigs, production facilities, and pipeline camps on the movements of caribou 

• Describe caribou reactions to aircraft 

• Discuss mitigative measures in relation to oil development 

• Includes appendix of annotated reports pertinent to caribou/oilfield interactions and the Eileen West 

End 

This annotation focuses only on caribou reactions to pipelines and other linear structures 

Data Quantity: 

• 35 publications dating from 1959 to 1983 

Analytical Methods: 

• Review of literature, with mapping of caribou movements along Kuparuk River in 1982 

Results: 

• Four types oflinear structures were evaluated-road with no traffic, road with traffic, pipeline with · 

road with no traffic, and pipeline adjacent to road with traffic-with only the last design substantially 

impeding caribou movements 

• Caribou often reacted strongly when crossing a road with traffic and tended to parallel roads with traffic more often than those without traffic 

• Although caribou may have hesitated upon initial approach, they crossed pipelines associated with 

roads with no traffic at a frequency similar to natural conditions 

• Caribou may parallel pipelines prior to crossing 

• Major factors affecting crossing of an elevated pipeline by caribou appear to be topography and insects 

• Crossing sites often occur near preferred habitat for travel such as river drainages, margins of lakes, 

sloughs, and ponds 

• During insect harassment, caribou may leave preferred habitat and encounter pipeline at less preferred 

habitats 

• Active selection for pipe height within the range of 60-170 in. has not been demonstrated and it appears that 5-ft-minimum pipe height in the absence of traffic allows passage of caribou 

• Caribou have shown selection for crossing at ramps, perhaps due to elimination of visual stimulus of 

elevated pipe 

Conclusions: 

Author discusses mitigative measures regarding pipelines and linear structures 

• Mitigative measures in place include 5-ft minimum height for elevated pipelines, installation of crossing ramps, and prohibition of construction activities during the mosquito season 

• Other measures should be taken, including spatial separation of pipelines from major roads, deflection 

of caribou around areas of intense development, traffic control program during July to minimize disturbance to caribou traveling to the coast for relief from mosquito harassment, and use of north/southoriented pipelines when possible to minimize encounters with caribou 

Peer Reviewed: No 

Curatolo, J. A. 1984. A study of caribou response to pipelines in and near the Eileen West End, 1983. 

Final report prepared for Sohio Alaska Petroleum Company, Anchorage, by Alaska Biological Research, Fairbanks. 32 pp. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk Oilfield; western Prudhoe Bay Oilfield; Central Arctic Herd 

Dates of Study: 

• Summer; postcalving; insect period; 25 June to 29 July 1983 

49 
Pipeline Characteristics: 

• Two different elevated pipelines, the Kuparuk Pipeline (Pipe Site) and pipeline to SOHIO S Pad (SPad pipeline) 

• Kuparuk Pipeline and S-Pad pipeline located 1.5 mi apart 

• Specific diameters and heights of pipelines not given 

• Distance between VSMs not specified 

• Height of S-Pad pipeline at least 20 ft above ground 

Study Design: 

• Behavioral observations from 10-ft-high tower and an observation blind situated on a 15-ft high riverbanl<: 

• Data from a control site was collected during 1981 and 1982 (see Curatolo et al. 1982, Curatolo and 

Murphy 1983; methods not repeated here) and compared with data collected from 2 sites, Pipe Site 

and S Pad, during 1983 after completion of S-Pad pipeline 

• Crossing success was not defined (presumed to be identical to Curatolo et al. 1982 and Curatolo and 

Murphy 1983) 

Objectives: 

• Determine if number and composition of caribou moving along the Kuparuk River during mosquito 

season differed between 1981 and 1982 

• Determine whether crossing frequency and pipe-height selection of the Kuparuk Pipeline differed 

among 3 years of study 

• Determine if caribou would cross multiple structures (2 pipelines and a road) 

• Determine if caribou routes of travel differed in 1982 before S-Pad pipeline was built, compared with 

1983 after construction 

Data Quantity: 

• 231 groups of caribou observed Pipe Site 1981-1983 

• 136 groups of caribou observed at control site 1981-1982 

• 36 groups of caribou observed at S-Pad pipeline 1983 

Analytical Methods: 

• Mapped movements in two areas 

• Described frequency of pipeline crossing both before and after new pipelines constructed in 1983 in 

two locations by insect activity, group type, and group size 

• Analyzed using chi-square tests of independence of crossing success before and after construction 

• Compared pipeline height at crossing locations with available heights, and pipeline height used 

(greater or less than 100 in.) compared to availability within 0.125 miles 

• Recorded numbers of mild, moderate, and strong reactions to pipelines 

Results: 

50 

• Quantified age and sex of caribou observed near Prudhoe Bay 1983, in the S-Pad area 1983, and the 

Pipe Site 1981 ~1983 during different time periods 

• Movement patterns of caribou in the Pipe Site (part of Kuparuk pipeline) were similar among all 

years of study ( 1981-1983) 

• Movement patterns of caribou near the S-Pad pipeline were similar between 1982 and 1983 

• The effects of mosquitoes on movement patterns and direction of travel are described 

• No significant differences in frequencies of caribou groups crossing the Kuparuk Pipeline during 

1981-1983 . 

• No significant differences in crossing frequencies among Pipe Site, S Pad, and control areas for all 

years 

• Within-site variation in crossing frequency was high, with frequencies consistently higher during periods of mosquito and oestrid fly harassment than during periods without insect activity 

• During insect-free periods, caribou show more randomly directed movements 

• During mosquito harassment, caribou must cross the pipeline as stimulus to reach the coast is high 

• During oestrid fly harassment, caribou are attracted to pipeline for fly relief 
• No differences in frequencies of crossings by different types or sizes of groups 

• During all years, an apparent selection for high pipe resulted from tendency of caribou to travel in 

riparian habitat in the eastern portion of study area, which happened to have consistently high pipe 

heights 

• When all pipe heights at VSMs within 0.125 miles of a group's route of travel were analyzed, no 

selection for high versus low pipe 

• 53% of crossings occurred at pipe heights> 100 in. and 47% of crossings occurred at heights <l 00 in 

• Reactions of caribou crossing Kuparuk and S-Pad pipelines were similar among years and sites 

• <20% of caribou crossing either pipeline reacted severely whereas 62% of caribou crossing a pipeline 

adjacent to a road with traffic reacted severely (Curatolo and Murphy 1983) 

• Roads with high traffic, about 1 vehicle/4 min (15 vehicles/hr), situated next to pipelines significantly 

reduced crossing success of caribou 

Conclusions: 

• Topographic features were important factors affecting local movements of caribou 

• Crossing frequencies at S-Pad and Kupamk pipelines were similar to control situation 

• Overall crossing frequency of caribou was not reduced by having to cross two separate pipelines 1.5 

mi apart 

• Percent of strong responses by caribou crossing both pipelines was low, indicating that pipelines 

alone may not be perceived by caribou to be an obstacle 

Peer Reviewed: No 

Curatolo, J. A. 1985. Caribou responses to the pipeline-road complex in the Kuparuk Oilfield, Alaska 

[abstract only]. Pages 62 in A. M. Martell and D.E. Russell, editors. Caribou and Human Activity: Proceedings of the First North American Caribou Workshop. 28-29 September 1983, Whitehorse, Yukon. 

Canadian Wildlife Service, Ottawa, Ontario. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk; Central Arctic Herd 

Dates of Study: 

• Summer: calving; postcalving; insect period; 22 June to 5 August 1981 and 4 June to 1 August 1982 

Pipeline Characteristics: 

• Not specified 

Study Design: 

• Behavioral observations at 4 study areas and 2 control sites 

Objectives: 

• Describe behavior, movement patterns, habitat preferences, and reactions to environmental and manmade stimuli 

Data Quantity: 

• Not described 

Analytical Methods: 

• Not described 

Results: 

• Caribou reacted with increasing intensity to road with no traffic, a pipeline, a road with traffic, and a 

pipeline associated with traffic 

• Within the range examined, caribou did not select crossing sites on basis of pipeline height 

• Insects and topography were most important factors influencing the selection of pipeline crossing 

sites, traveling through all habitats to escape insects, but following ridges when insects were absent 

Conclusions: 

• Abstract was limited to results 

Peer Reviewed: Yes 

51 
Curatolo, J. A., and S. M. Murphy. 1983. Caribou responses to the pipeline/road complex in the Kuparuk Oilfield, Alaska, 1982. Final report prepared for ARCO Alaska, Inc., Anchorage, by Alaska Biological Research, Fairbanks. 81 pp. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• Summer; late calving/postcalving; insect period; 4 June to 1 August 1982 

Pipeline Characteristics: 

• Kuparuk Pipeline, diameter 16 in., elevated to minimum of 5 ft at VSMs 

• 2 study areas, each with different pipe/road characteristics 

• Pipe site contained Kuparuk Pipeline and no road (Spine Road was 2 mi north of site), pipe elevated 

60-170in 

• Pipe-road site contained Kuparuk Pipeline adjacent to Spine Road, pipe elevated 60-110 in 

Study Design: 

• Behavioral observations conducted from towers 

• 4 study plots, including 2 study (treatment) plots with pipelines and 2 control (reference) plots south 

of each treatment plot 

• Successful crossing defined as >50% of group members crossing the pipeline (and road, if present) 

• Compared proportion of caribou entering the control plots and crossing the northern border (representing hypothetical pipelines) to proportion of caribou entering treatment plots and crossing the 

northern border ( consisting of actual pipelines/roads) 

Objectives: 

• Determine the effects of the Kuparuk pipeline/road complex on caribou movements, emphasizing 

crossing success and routes of travel 

• Determine whether caribou preferred certain habitats, pipeline heights, or pipeline configurations for 

crossing sites 

• Determine reactions of caribou to pipelines and roads under different environmental conditions 

Data Quantity: 

• 3,723 caribou observed, classified by sex and age 

Analytical Methods: 

• Compared treatment sites with control sites 

• Compared pipeline height to availability in 10-in. increments, using chi-square tests 

• Compared crossings at pipe <l 00 in. to pipe> I 00 in., and number of crossings by different habitat 

types 

Results: 

52 

• 22% of caribou in study area classified as yearlings 

• Overall number of caribou in area decreased compared to 1981 with fewer cow-calf groups in 1982, 

but more bull groups than in 1981 

• Crossing frequency was lowest during calving and postcalving (pre-insect emergence), although 

sample sizes were small 

• Crossing frequency increased during the mosquito season, but was significantly lower in the piperoad site than all other study plots, a finding consistent with 1981 data 

• No significant differences in crossing frequency were found among the 4 study plots during oestrid fly 

harassment, compared to 1981 when crossing frequency was lowest at pipe-road site 

• There was a significant seasonal difference in crossing frequency at pipe and pipe-road sites, but not 

in the control plots 

• Crossing frequencies at pipe site during mosquito and oestrid fly seasons were similar, whereas it was 

considerably lower during the calving/postcalving season 

• Crossing frequency at pipe-road site was similar during the calving/postcalving and mosquito season, 

whereas it was higher during oestrid fly season 

• Multiple crossings by the same groups occurred more often during oestrid fly season 
• At pipe-road site, caribou showed no preference for pipe height 

• Although height selection at the pipe site was not random, there were no consistent trends toward 

selection of low or high pipe 

• Factors other than pipe height seemed to influence crossing-site selection 

• No significant differences were found in selection of low pipe ( < 100 in.) or high pipe (> 100 in.) during either mosquito or oestrid fly harassment, although sample sizes were small 

• When insects were absent, caribou used higher pipe heights significantly more 

• Selection of high pipe heights during insect-free periods may be related to topography rather than 

pipe-height preference 

• In presence of insects, harassed caribou tended to parallel pipeline, encountering a similar frequency 

of low and high pipeline 

• Group crossings in 1981 and 1982 showed no significant difference in crossing sites based on whether 

or not caribou could see tundra across the pipeline, a result differing from other studies that suggested 

caribou avoid high berms that restrict their vision 

• At pipe site, 18% and 16% of groups crossed over buried pipeline in 1981 and 1982, respectively 

• At pipe-road site, 5% and 6% of groups crossed over buried pipeline in 1981 and 1982, respectively 

• At both sites, buried pipeline accounted for <1 % of the pipeline, so crossing frequencies were significantly greater than expected based on availability 

• Pipe configuration at pipe-road site may have contributed to smaller percentage of caribou using 

buried sections; pipe crossed under road, but when it reappeared on the other side of the road, it paralleled it before crossing back 

• Groups· tended to fragment at the pipe-road site, which may have been related to traffic on road; yearlings tended to be left behind and often appeared disoriented 

• Overall rates of movement were significantly different between seasons 

• Caribou were relatively sedentary during calving and postcalving compared to mosquito and oestrid 

fly seasons; rate of movement was highest during insect harassment 

• No significant differences were found in movement rates among study plots during calving/postcalvmg 

• No significant differences were found in movement rate between pipe site and pipe control, but caribou at pipe-road site traveled significantly faster than caribou in the pipe-road control 

• During the oestrid fly season, caribou spent more time standing 

• No significant differences were found in movement rates between study areas during oestrid fly harassment 

• East-west travel, indicating that caribou were paralleling the Kuparuk pipeline, was greater at both 

treatment sites during 1981 and 1982 than controls, but differences were not significant 

• Groups attempting to cross in the pipe-road site often paralleled the pipeline, with vehicles causing 

caribou to run away from road 

• During late July-early August 1981 and 1982, 90% of the distance traveled by caribou groups was on 

gravel surfaces, such as roads, pads, and well sites, corresponding with presence of oestrid flies 

• Caribou showed least reaction to crossing roads, followed by a pipeline alone, a road with traffic, and 

a pipeline paralleling a road with traffic 

• Caribou showed significantly more strong reactions when crossing pipeline associated with traffic 

compared with any other linear structure 

• 91 % of 4,668 caribou that crossed roads with no traffic showed no reaction, 3% showed mild reactions, and 1 % showed moderate reactions 

• 55% and 76% of 2,263 caribou that crossed the pipeline showed no or mild reactions during mosquito and oestrid fly harassment, respectively 

• 7 5% of 2,263 caribou crossing buried section of pipe showed no behavioral reaction and 25% crossing under elevated pipeline showed no reaction 

• 5,016 caribou were observed crossing roads with traffic, and mainly exhibited moderate or strong 

reactions during all seasons 

53 
• 91 % and 17% of 341 caribou crossing a pipeline associated with traffic showed moderate or strong 

reactions during the mosquito and oestrid fly season, respectively 

• Average rate of vehicle passage on Spine Road was 1 vehicle/4 min (15 vehicles/hr) 

• Strength of behavioral reactions by caribou depended on proximity of vehicles; most strong reactions 

occurred when caribou encountered vehicles while crossing roads 

Conclusions: 

• Most caribou showed no reaction when crossing road with no traffic 

• Although caribou freely crossed a road with traffic and a pipeline, strong reactions were more frequent when crossing roads with traffic 

• Caribou crossed pipelines associated with road and traffic at significantly lower frequencies than 

either structure by itself, and showed an increase in number and strength of reactions upon approach 

and crossing, increased rate of movement, increase in paralleling of pipeline, and increase in group 

splitting 

• Crossing sites may have been influenced more by habitat than by pipe height, with caribou selecting 

drier habitat for travel 

• Although caribou under mosquito harassment had high crossing frequencies, the greatest number of 

strong reactions to linear structures were recorded during this period 

• Caribou did not react as strongly to linear structures when under oestrid fly harassment, showing an 

increase in multiple pipeline crossings, use of gravel, decreased reactions when crossing pipelines associated with traffic, and increased crossing success 

Management recommendations include: 

• Separating roads with traffic from elevated pipelines 

• Strategic placement of crossing ramps or other sections of buried pipe 

• Conduct a region-wide analysis of caribou movements, distribution, and habitat use, to provide basis 

for determining where site- specific mitigation measures would be most effective 

Peer Reviewed: No 

Curatolo, J. A., and S. M. Murphy. 1986. The effects of pipelines, roads, and traffic on the movements 

of caribou, Rangifer tarandus. Canadian Field-Naturalist 100: 218-224. 

Study Location/Herd: 

• Alaska; North Slope; Arctic Coastal Plain; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• Insect period; late June; July; early August; 1981-1983 

Pipeline Characteristics: 

• Elevated to minimum height of 1.5 m 

• Diameter 40 cm 

• Areas bordering roads and pads with varying traffic levels 

• Ramps created as crossing structures by burying pipelines; ramp widths 20, 30, and 50 m 

Study Design: 

• Behavioral observations conducted from towers; no set schedule for observations, rather an effort to 

observe caribou when present for as long as present 

• Observations conducted at 7 sites, including 2 control (reference) sites 

• Groups were considered successful in crossing the pipeline (and road, if present) if >50% of group 

members crossed 

• Compared proportion of caribou entering the control sites and crossing the northern border (representing hypothetical pipelines) with proportion of caribou entering study plots and crossing the northern 

border ( consisting of actual pipelines/roads) 

Objectives: 

• Quantify crossing frequency of caribou encountering pipelines and roads 

• Evaluate whether pipeline height affected selection of crossing sites 

• Evaluate whether ramps were preferred as crossing sites 

54 
Data Quantity: 

• 794 caribou groups comprising 21,912 caribou were observed at 7. different study sites, including 2 

control sites 

Analytical Methods: 

• Compared crossing success in 7 plots with pipelines, roads and pipelines, or controls (hypothetical 

pipelines) 

• Compared crossing frequencies with chi-square tests and compared pipeline height selection with 

Mann-Whitney tests 

Results: 

• Number and movement patterns of caribou near pipelines depended on presence of insects 

• When mosquitoes were present, caribou traveling north represented 80% of observations and when 

mosquitoes were absent, 77% of observations were caribou traveling south 

• When oestrid flies were present, caribou exhibited nondirectional movement, resulting in repeated 

crossings of pipeline by groups; caribou tended to seek relief from flies in shade of pipeline 

• Caribou reacted more severely when crossing the road bordered by a pipeline compared to either a 

road or a pipeline 

• Crossing frequency was lowest where traffic frequency next to the pipeline was highest 

• There was no difference between the percentage of cow-calf groups and bull groups that crossed the 

pipeline 

• Large groups (> 100 caribou) tended to be less successful in crossing pipelines bordered by a road 

than smaller groups, but there was no difference in crossing frequency at sites with only a pipeline 

• Mean pipeline height at crossing sites did not differ significantly from the mean pipeline height 

• Crossing ramps were used more frequently than expected based on availability 

Conclusions: 

• Caribou readily crossed a single _structure such as a pipeline or a road, but less frequently crossed a 

pipeline bordered by a road 

• Separation of pipelines and roads may facilitate caribou passage 

• The minimum pipeline height of 150 cm was adequate to accommodate caribou crossings 

• Caribou used ramps to cross the pipeline, although ramps may have been less effective in areas with 

heavy traffic 

Peer Reviewed: Yes 

Curatolo, J. A., S. M. Murphy, and M.A. Robus. 1982. Caribou responses to the pipeline/road complex 

in the Kuparuk Oilfield, Alaska, 1981. Final report prepared for ARCO Alaska, Inc., Anchorage, by 

Alaska Biological Research, Inc., Fairbanks. 63 pp. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• Summer; postcalving; insect period; 22 June to 5 August 1981 

Pipeline Characteristics: 

• Kuparuk Pipeline 

• Pipe site study plot (1.5 mi long by 0.5 mi wide) contained a pipeline and no road, pipeline height 

range 60-170 in. 

• Pipe-road study plot (1.25 mi long by 0.5 mi wide) paralleled the Spine Road, distance unspecified, 

pipeline height range 60-110 in. 

• Diameter of pipeline unspecified 

Study Design: 

• Behavioral observations conducted from towers in plots 

• Crossing was considered successful if >50% of group members crossed the pipeline (and road, if 

present) 

55 
• Movement data was compared to two control sites similar in area to study sites and located 1-2 mi 

south of each study site 

• Compared proportion of caribou entering the control areas and crossing the n011hem border (representing hypothetical pipelines) to proportion of caribou entering study plots and crossing the northern 

border consisting of actual pipelines/roads 

Objectives: 

• Evaluate effects ofKuparuk pipeline/road complex on caribou movements, emphasizing crossing success and routes of travel 

• Evaluate specific pipe configurations, places, or heights that caribou selected for crossing 

• Quantify reactions of caribou to pipeline and road under different environmental conditions 

Data Quantity: 

• 5,229 caribou were observed and classified to sex and age during the study 

Analytical Methods: 

• Chi-square tests of crossing success at 4 different plots (2 pipeline sites, 2 controls) and among different height categories 

• Conducted chi-square tests of use of areas of buried pipe 

• Used Kruskal-Wallis test to compare rate of group movement among plots 

• Used chi-square test to compare direction of travel among sites 

Results: 

56 

• 65% of 221 groups observed in the pipe site crossed the pipeline at least once, compared with 67% of 

92 groups which crossed the corresponding boundary of the control site 

• 41 % of 113 groups observed in the pipe-road site crossed the pipeline at least once, compared with 

67% of 69 groups which crossed the corresponding boundary of the control site 

• Impossible to know what percent of caribou classified as unsuccessful actually "intended" to cross the 

pipeline 

• During mosquito and oestrid fly harassment, crossing success at pipe site, pipe control, and pipe-road 

control were similar and significantly higher than at the pipe-road site 

• At pipe site, 58% of 67 groups that entered study area from south and exited to no1ih crossed the 

pipeline, compared with 48% of 29 groups at control site 

• At pipe-road site, 27% of 37 groups that entered study area from south and exited to north crossed the 

pipeline, compared with 83% of 12 groups·at control site 

• Percentage of crossings at each site was similar among cow-calf groups, bull groups, and various 

group size categories 

• Repeated crossings of pipeline involved 70% of individuals and 30% of groups of 2-11 caribou and 

occurred mostly during oestrid fly harassment 

• At pipe-road site, no significant differences were found in frequency of pipeline crossings among 

pipe-height categories 

• At pipe-road site, <1 % of pipe length was buried, but 7% of groups crossed this section, significantly 

greater than availability 

• At pipe-site, significant differences were found in crossing frequency among pipe heights; heights 

70-79, 80-89, and 110-119 in. were used less than expected, whereas heights >130 in. were used 

more than expected 

• At pipe-site, <l % of pipe length was buried, yet 17% of groups crossed this section, significantly 

greater than availability · 

• Habitat within each study site was quantified 

• East-west travel within both pipeline sites was significantly greater than within the control sites, indicating paralleling movements 

• Rate of group movement for the entire period and both insect periods was significantly greater at 

pipeline sites than at control sites, but there were no differences between pipeline sites or between 

controls 

• Average rate of movement during oestrid fly harassment was greater than during mosquito harassment 
• Cow-calf groups moved faster than bull groups 

• Few behavioral reactions of caribou to roads without traffic were noted 

• Caribou spent significantly more time standing and traveling on roads during oestrid fly harassment 

than during mosquito harassment 

• In the absence of traffic, 44% of 32 caribou showed no reaction while crossing the Kuparuk pipeline, 

19% showed mild reactions, 16% moderate reactions, and 22% strong reactions 

• In the presence of traffic, 28% of 25 caribou showed mild reactions while crossing the corridor, 16% 

showed moderate reactions, and 56% showed strong reactions 

• Caribou approaching the pipeline as a vehicle passed usually retreated in the opposite direction 

• Caribou generally moved greater distances in reaction to vehicles during the mosquito season than 

during the oestrid fly season 

• Caribou often approached the pipe slowly, then trotted under the pipe for several meters, and slowed 

again after crossing 

• Some caribou crossed by crouching with legs bent and head low to the ground even though the pipeline afforded sufficient clearance 

• Caribou that showed strong reactions, often yearlings, during crossings often were left behind on the 

south side of the pipeline 

• Crossing by a group of caribou often was initiated by a single individual 

Conclusions: 

• Elevated pipeline at pipe site did not appear to affect caribou movements 

• Caribou responded to pipelines more often during mosquito harassment than during fly harassment 

• Caribou tended to select crossing sites at heights> 130 in., but this may have been due to local topography 

• Vehicles moving on road adjacent to a pipeline evoked disturbance behavior 

• Caribou showed strong selection for crossing buried sections of pipeline 

Authors made these suggestions: 

• Use ramps in areas of concentrated caribou movements 

• Regulate vehicle traffic during mosquito season to reduce disturbance to caribou by consolidating 

work into localized areas, limiting numbers of vehicles along roads, allowing heavy traffic at night 

when mosquito levels arc low 

• Separate road and pipeline by at least 1 mi 

• Consider making pipeline design consistent with natural topography and environmental stimuli 

Peer Reviewed: No 

Curatolo, J. A., and A. E. Reges. 1986. Caribou use of pipeline/road separations and ramps for crossing 

pipe/road complexes in the Kuparuk Oilfield, Alaska, 1985. Final report prepared for ARCO Alaska, 

Inc., and Kuparuk River Unit, Anchorage, by Alaska Biological Research, Fairbanks. 106 pp. 

Study Location/Herd: 

• Alaska; North Slope; Kuparnk Oilfield; Oliktok Point Road; Central Arctic Herd 

Dates of Study: 

• Summer; postcalving; insect season; 27 June to 31 July 1985 

Pipeline Characteristics: 

• Elevated pipeline 

• 6 study plots located along Oliktok Point Road, with different road/pipe and ramp configurations 

• Ramps ranged in length 120-280 ft, width 30-38 ft, and thickness 8-12 ft 

• Mean pipeline/road separation distance for each area ranged from 223 to 676 ft 

Study Design: 

Behavioral observatio;ns conducted from towers or from pickup trucks parked on road 

Objectives: 

• Compare the effectiveness of pipeline/road separations with the effectiveness of conventional crossing ramps 

57 

I 
• Compare the effectiveness of pipeline/road separations including ramps with the effectiveness of 

pipeline/road separations lacking ramps 

• Determine minimum separation distance required between a pipeline and road to increase crossing 

success 

• Examine the impact of traffic on crossing success 

• Evaluate the effectiveness of a new ramp design 

Data Quantity: 

• Observations of 15,822 caribou among 6 study plots 

Analytical Methods: 

• Compared caribou reactions and crossing success among plots with different road/pipeline separation 

distances using chi-square tests 

• Used chi-square tests to compare crossing success before and after blocking access to ramps 

Results: 

• Most (62%) observations occurred during periods of no insect activity; 18% and 20% occurred during 

periods when mosquitoes and oestrid flies were present, respectively 

• General lack of mosquitoes in 1985 season resulted in few observations during that important insect 

condition, compared with previous years 

• Most caribou that displayed strong behavioral reactions to pipeline and vehicles were within 300 ft of 

stimuli 

• 8.9% showed strong reactions to vehicles, 5.9% to both pipelines and vehicles, and 2.9% to pipelines 

• 80% of caribou displayed strong reactions to vehicles within 400 ft; 19% reacted strongly at 400-800 

ft; beyond 800 ft, almost no caribou reacted strongly 

• 65-99% of caribou crossed pipeline/road complexes, except in one study area where traffic rates 

exceeded 5 vehicles/hr and insects were absent; separation distance between pipeline and road in this 

area did not exceed 300 ft, while in Qther areas at least 42% of pipeline length was >300 ft from road 

• Number of caribou crossings was significantly less than expected for pipeline/road separation distances <300 ft. 

• Blocking ramps midway through study did not seem to affect the proportion of caribou successfully 

crossing the pipeline 

Conclusions: 

• Caribou frequently crossed pipeline/road complexes in all study plots, except in one plot where traffic 

rates were high 

• Recommended minimum separation distance of 400 ft between pipeline and road for areas of high 

traffic and heavy use by caribou 

• Sections of adequate separation (>400 ft) should be at least 1/4- to 1/2-mi long 

• Dimensions of pipeline/road separations should be site-specific to allow for variations in caribou 

movement due to insect activity, traffic rates, geographic location, and directional orientation of pipeline/road corridors 

• Although caribou used ramps preferentially, they were not necessary for successful crossings; authors 

suggested that the ramps they studied should be lower and longer to facilitate their use by caribou 

Peer Reviewed: No 

Eide, S. H., S. D. Miller, and M.A. Chihuly. 1986. Oil pipeline crossing sites utilized in winter by moose 

and caribou in southcentral Alaska. Canadian Field-Naturalist 100: 197-207. 

Study Location/Herd: 

• Alaska; southccntral; Copper River drainage; Gulkana River drainage; Nelchina Herd 

Dates of' Study: 

• Winter; 2-5 survey days monthly during October-April 

Pipeline Characteristics: 

• Trans-Alaska Pipeline 

• Elevated pipeline, average height at VS Ms 7.4 ft, range I~ 13 ft 

58 
• Pipeline diameter 5 ft (including insulation) 

• Vertical support members (VSM) spaced at 60-ft intervals 

• Crossing structures included underpasses >IO ft high and 60 ft long; buried sections averaging 0. 7 mi 

in length; short buried sections (sag-bend crossings) <60 ft long 

Study Design: 

• Track surveys to identify where moose and caribou crossed the pipeline 

Objectives: 

• Evaluate use of crossing structures designed to allow free passage of moose and caribou 

• Evaluate where animals chose to cross pipeline 

Data Quantity: 

• 1,309 moose track encounter.s 

• 6,304 caribou track encounter.s 

Analytical Methods: 

• Compared pipeline height at crossing sites with pipeline height availability in I -ft categories, and 

amount of buried vs. elevated pipeline, using chi-square goodness-of-fit tests 

• Subdivided study area into smaller subsections and tested separately 

Results: 

• 148.1 km of pipeline was surveyed, with 7.3% of segments (defined as area between two adjacent 

VSMs with height of section calculated by averaging heights at the 2 VSMs) at least 3.1 m (10 ft) 

above ground 

• Average height of designated big game crossings (DBGCs) 10.3 ft, with range of 6.5~ 14.8 ft 

• For both moose and caribou, 82% and 75%, respectively, of average heights at the two VSMs bordering crossing points were within ~ 1 ft of the height at the actual crossing point, indicating that it was 

appropriate to use "as-built" specifications to estimate the availability of vertical clearance heights 

under the pipeline 

• Moose did not cross under sections of pipeline with vertical heights in proportion to their occurrence, 

selecting against sections <5 ft in height; only 10 crossings occurred at heights <5 ft 

• For all sections of pipeline <11 ft height, 42 (3.2%) of moose encounters were considered deflections 

where moose approached, but did not cross; no deflections occurred at buried sections 

• 16% of moose that were classified as deflecting eventually crossed the pipeline after paralleling it for 

several sections 

• 65% of sections moose used to cross the pipeline were crossed by a single set of tracks, with a maximum of 8 tracks at a DBGC 

• Moose used sections with buried pipe significantly less often than sections with elevated pipe 

• Moose did not select for DBGCs 

• 70.3% of caribou tracks recorded were eastbound during fall migration 

• In some areas, the frequency distribution of heights measured at crossings differed significantly from 

expected values based on distribution of available pipeline heights 

• Overall, caribou selected against vertical clearances <7 ft; pattern for positive selection was less clear, 

but seemed to select for clearances >8 ft 

• In analysis by subsections of pipeline, caribou showed negative selection for lowest clearance categories and positive selection for higher categories 

• 2. 7% of caribou approaching the pipeline deflected, with 99% of these occurring at elevated pipe 

• Deflections by caribou were seen at all pipeline heights, except for those <5 ft and> 12 ft, but crossings at these heights were rare 

• In 1.4% of all crossings, caribou crossed under a pair ofVSMs rather than in the section between 

them, meaning that they had about half the vertical clearance because of the cross members on the 

VSMs 

• Lowest vertical height of a caribou crossing was 3 .2 ft and under a VSM 

• 13 caribou crossings occurred at heights <4 ft, all of which were under a VSM 

• 5 or more sets of caribou tracks were observed at 33.7% of crossed segments 

59 
In some sections, caribou selection for buried pipe was highly significant, using those sections 2-4 

times more often compared to expected values 

• This result may not mean that caribou actively looked for buried sections, however, because most buried sections were located in corridors known to be used by caribou before constrnction 

• Only 2 deflections of caribou from buried sections were seen 

• Caribou did not select for DBGCs; 30 caribou deflected at 2 DBGCs, both of which had vertical 

clearances > 10 ft 

• 23 caribou crossings occurred at 2 sag-bends; 19 caribou crossed under an elevated section adjacent 

to a sag-bend while 17 caribou also crossed over this same sag-bend; one caribou deflected at a sagbend 

Conclusions: 

• Studies demonstrating selectivity for or against pipeline features are complicated by the nonrandom 

distribution of the features 

• Caribou readily used buried segments, which may indicate active selection or continued use of traditional migration routes in which those special crossings were placed 

• No consistent pattern of selection was seen for moose crossings, but caribou tended to avoid pipeline 

<7 ft in height 

• No evidence that moose or caribou crossings were facilitated by DBGCs or sag-bends, but caribou 

might use sag-bends if they occurred more frequently and were longer 

• Both moose and caribou populations appeared unaffected by the presence of the pipeline 

• Authors suggested movements could be inhibited during severe winters with deep snow and suggest 

further study of this possibility 

Peer Reviewed: Yes 

Fancy, S. G. 1982. Movements and activities of caribou at Drill Sites 16 and 17, Prudhoe Bay, Alaska: 

The second year. Final report prepared for Prudhoe Bay Unit Owners, by LGL Alaska Research Associates, Inc. 48 pp. 

Study Location/Herd: 

• Alaska; North Slope; Prudhoe Bay; Central Arctic Herd 

Dates of Study: 

• Summer; postcalving; insect period; 1 July-IO August 1981 

Pipeline Characteristics: 

• Flow lines from drill sites elevated ~2 m above ground on VSMs; spacing interval unspecified; diameter unspecified 

• Study area contained both a pipeline bordered by a road and a pipeline separated from the road by 

~l km 

Study Design: 

Behavioral observations conducted from towers in a 9-km2 study (treatment) plot and a 9-km2 control 

(reference) plot 

• Successful group crossing was not defined, but author mentioned that if a group split while attempting to cross a structure, the movements of each new group were recorded; however, repmi does not 

directly discuss proportions of groups successfully crossing structures 

• Crossing behavior of groups passing within 500 m of a structure were analyzed 

• Roads, pipelines, drill pads, and buildings collectively referred to as structures 

• Observations mostly made during daytime hours 

Objectives: 

60 

• Determine if caribou movements through the area of Drill Sites 16 and 17 were random or whether 

they show preferred movqnent patterns 

• Determine if caribou avoided drilling strnctures and associated human activity 

• Detennine if the distance between caribou groups and infrastructure affected movement and activity 

patterns, and if so, to approximate the distance at which this change occurred 
• Detennine if response of caribou groups to drilling structures and human activity differs according to 

sex and age composition of group 

• Assess combined effects, if any, of flow lines, roads, traffic, human activities, and drilling structures 

on caribou; provide rationale for assessment 

Data Quantity: 

• 99 groups approached within 500 m of road, pipeline, or drill pad 

Analytical Methods: 

• Chi-square tests of crossing categories (no encounter, crossed structure directly, detoured around 

structure, reversed direction; groups crossing after turning >90 degrees dropped from analysis) by 

group size, presence or absence of calves, insect category, entry location; mapping of movements 

Results: 

• This rep011 focused on movement patterns of caribou in the eastern Prudhoc Bay Oilfield under varying insect conditions and is not applicable to the effects of pipeline height on crossing success of 

caribou 

• In addition, no distinction was made between pipelines, roads, drill sites, and buildings 

• Results arc not summarized in this annotation; see annotation for Fancy (1983) 

Conclusions: 

• Conclusions are not summarized in this annotation; see annotation for Fancy ( 1983) 

Peer Reviewed: No 

Fancy, S. G. 1983. Movements and activity budgets of caribou near oil drilling sites in the Sagavanirktok River floodplain, Alaska. Arctic 36: 193-197. 

Study Location/Herd: 

• Alaska; Nmih Slope; Prudhoe Bay; Central Arctic Herd 

Dates of Study: 

• Summer; postcalving; insect period; I July-IO August 1981 

Pipeline Characteristics: 

• Dimensions of pipeline in study area not specified 

• Study area contained both a pipeline bordered by a road and a pipeline separated from the road by 

~lkm 

Study Design: 

Behavioral observations from towers in a 9-km2 study (treatment) plot and a 9-km2 control (reference) plot 

• Successful crossing was not defined, but author mentioned that if a group split while attempting to 

cross a structure, movements of each new group were recorded; however, proportions of groups successfully crossing structures were not specifically reported 

• Crossing success of structures was recorded with roads, pipelines, drill pads, and buildings collectively referred to as structures 

• Crossing behavior of groups passing within 500 m of a structure were analyzed 

• Observations mostly made during daytime hours 

• This publication originated from a report (Fancy 1982) 

Objectives: 

• Determine if movements and activities of caribou were significantly altered by presence of drilling 

structures and human activities 

• Disturbances included roads, pipelines, drill pads, buildings, vehicle traffic, presence of humans 

Data Quantity: 

• 1,035 caribou were observed in the drill-site study plot, compared with 998 in control plot 

• 99 groups approached within 500 m of road, pipeline, or drill pad 

Analytical Methods: 

• Mapped movements; recorded movement rates, activity budgets 

61 

I 
• Compared movement rates and activity budgets with analysis of covariance (ANCOVA), using proportion of calves as a covariate 

• Used descriptive statistics to compare crossing success in drill-site plot with crossing success in control plot (hypothetical infrastructure) 

Results: 

• Mean movement rates by caribou in drill-site plot during periods of low and high insect levels were 

not significantly different than those in the control plot 

• No relationship between rate of movement and proportion of calves in groups during periods of low 

and high insect levels 

• In both plots, groups harassed by mosquitoes and/or oestrid flies moved significantly faster than unharassed groups 

• 1 7 caiibou groups crossed both the control grid and drill site grid and remained intact; movement rate 

for these groups on the drill site was less than that on the control grid 

• Proportion of time spent lying and feeding on drill site grid was not significantly different from that 

on the control grid during periods of low and high insect harassment 

• Insect harassment has significant effect on activity with caribou spending less time lying and feeding 

during high insect levels compared to low insect levels 

• During high insect levels, proportion of calves in group was not significantly related to proportion of 

time lying and eating, but during low insect levels, there was a significant inverse relationship on both 

grids 

• Most groups encountering elevated pipeline hesitated briefly before quickly crossing underneath 

• Caribou sought out relief from insects in the shade of infrastructure, but insect-relief areas are commonly available on the delta, making the benefit of these structures unknown 

• 70.7% of caribou crossed the first structure encountered, 19.2% detoured around the drill site, and 

10.1 % reversed direction and left the grid 

• Group.s that detoured around the drill site appeared to alter their movements while >2 km away from 

nearest structure 

• Structures of the drill grid were superimposed on a map of the control site; 8% of 87 groups detoured 

around the hypothetical "structure", and 1.1 % reversed their direction and left the grid 

• Used the above figures for the control grid to adjust those determined for the control site, concluding 

that 20% of groups altered their movements in response to infrastructure 

• Calf percentage on the drill grid in 1980 was 23.9%, similar to ADFG regional estimate of 21 % 

calves 

• Calf percentage on the control (10.5%) and drill sites (12.5%) in 1981 was lower than the ADFG 

regional estimate of 28% 

• Traffic levels during the last week of July 1980 were nearly twice those in 1981, which may have 

contributed to the difference; both gravel pads were enlarged in 1980, creating noise from construction and higher levels of human activity 

• Low calf percentage was likely explained by annual variation in use of drainages near study area 

rather than by maternal cow avoidance of infrastructure 

Conclusions: 

• Results should be interpreted carefully because individual caribou that were sensitive to human activities were able to detour around the east side of the study area 

• Pipeline in study area was elevated ~ 2 m above ground to allow for passage of caribou; however, in 

some areas of oilfield pipe heights arc not sufficiently elevated 

Peer Reviewed: Yes 

Fancy, S. G., R. J. Douglass, and J.M. Wright. 1981. Movements and activities of caribou at Drill Sites 

16 and 17, Prudhoe Bay, Alaska. Final report prepared for Prudhoe Bay Unit Owners, Anchorage, by 

LGL Alaska Research Associates, Inc. 48 pp. 

62 
Study Location/Herd: 

• Alaska; North Slope; Prudhoe Bay; Central Arctic Herd 

Dates of Study: 

• Summer; postcalving; insect period; 1 July-15 August 1980 

Pipeline Characteristics: 

• No flow lines (feeder pipelines) in place yet at these newly constructed drill sites, although VSMs and 

gravel work pads were present 

• Characteristics of pipelines that may have been present during this first year of study were not described 

• Study area contained roads along which flow lines would be constructed 

Study Design: 

• Behavioral observations from towers in a 9-km2 study plot 

• Successful group crossing was not defined, but author mentioned that if a group split while attempting 

to cross a structure, movements of each new group were recorded; however, report does not directly 

discuss proportions of groups successfully crossing structures 

• Crossing behavior of groups passing within 500 m of a structure were analyzed 

• Roads, pipelines, drill pads, and buildings collectively referred to as structures 

• Observations mostly made during daytime hours 

Objectives: 

• Determine if caribou movements through the area of Drill Sites 16 and 17 were random or whether 

they showed preferred movement patterns 

• Determine if caribou avoided flow lines, roads, associated strnctures or adjacent areas 

• Estimate the distance at which caribou began to respond to strnctures 

• Determine if response of caribou groups to drilling structures and human activity differed according 

to sex and age composition of group 

Data Quantity: 

• 2,432 observations of 80 caribou groups 

Analytical Methods: 

• Compared rate of movement at two-minute intervals for caribou groups with distance from infrastructure 

• Direction of movement was compared using circular statistics 

• Extreme autocorrelation in the data set precluded many statistical analyses 

• Used group means of rate of movement to compare rate of movement and distance from infrastructure 

• Compared crossing pattern categories of groups with sex and age classification, group size, and direction of movement using chi-square tests 

Results: 

• High levels of construction activity, averaging 340 vehicles/day on drill-site roads 

• Impossible to separate effects of structures from effects of human activity, so authors felt study objectives had not been met 

• Movements of caribou through area were not random 

• Of groups approaching within 500 m of structures, 31 % detoured around it or reversed direction 

• Crossing pattern was not significantly affected by group size, study area entry location, or group composition 

• During low levels of mosquito harassment, there was an inverse relationship between rate of movement and distance from structure; caribou farthest from structures bedded down more often, and ran 

and walked less 

• Rate of movement was not significantly related to distance from structures 

• Level of mosquito harassment had greatest effect on rates and direction of caribou movements, with 

rate being significantly higher and direction of movement being northerly during periods of high mosquito levels 

• Groups composed of only females had the highest movement rates whereas bull groups had lowest 

movement rates 

63 
• Group size was inversely related to rate of movement, with smaller groups moving faster than larger 

groups 

Conclusions: 

• There was no control plot in this study, limiting extrapolation of data (see Fancy 1982, 1983 for results of second year of study) 

• There was considerable construction activity during the study; distance from caribou to nearest structure was usually different than distance to nearest human activity 

• Because human activities may affect caribou behavior, results of this study are of questionable value 

Peer Reviewed: No 

Hanson, W. C. 1981. Caribou (Rangffer tarandus) encounters with pipelines in northern Alaska. Canadian Field-Naturalist 95: 57-62. 

Study Location/Herd: 

• Alaska; North Slope; Prudhoe Bay; Central Arctic Herd 

Dates of Study: 

• Summer 1971, 1972 

Pipeline Characteristics: 

• Pipe diameter 1.2 m 

• Fully to partially buried, resulting in 0.8-1. 7 m barrier resulting from berms after fill placement 

• Berms with 3: 1 slope 

Sections with 3-m-tall metal deflection poles 

• Pipeline adjacent to facility with diesel generators and haul road with traffic 

Study Design: 

• Behavioral observations from platform 

Objectives: 

• Record reactions of caribou encountering the berm of a buried pipeline 

Data Quantity: 

• 21 encounters 

Analytical Methods: 

• Behavioral description of caribou encounters with berms 

Results: 

• Caribou readily crossed areas where benn was <1.2 m 

• Crossing behavior varied among different caribou 

• Caribou avoided areas where large pools of water formed due to melting snow and subsidence 

• Most caribou were wary of deflection poles 

Conclusions: 

• Berms may form visual barriers to traveling caribou, preventing them from crossing 

• Disturbance may be moderated by creating berms <1.2 min height 

Peer Reviewed: Yes 

Hemming, J.E. Undated. Wild reindeer and pipelines in north central Siberia. Unpublished report of 

an exchange visit under terms of USA/USSR Environmental Protection Agreement. Project V-2 Ecosystems of Northern Regions. 8 pp. 

Study Location/Herd: 

• Russia; central Siberia; wild reindeer 

Dates of Study: 

• Late 1960s, early 1970s 

Pipeline Characteristics: 

• 2 low-elevation pipelines built parallel to one another, separated by 0.3 to 2.5 mi 

64 
• 28-in. diameter 

• Height unspecified 

• Crossing structures included a few wooden ramps over the pipeline, and elevated loop crossings (portals) 200-325 ft wide and 10-20 ft high and adjacent to each other in both pipelines 

• Pipelines built during 1968-1972 from Messoyakha to Norilsk and parallel to existing railroad 

• Pipelines bisect portion of migratory route of Taimyr Peninsula wild reindeer herd 

Study Design: 

• Report on visit to Siberia to meet with Soviet biologists 

• Discussed common interests in management and ecology of domestic and wild reindeer 

Objectives: 

• Report observations related to the effects of large-diameter pipelines on movements of wild reindeer 

Data Quantity: 

• Various interviews with Russian officials during 20 August-5 September 1974 

Analytical Methods: 

• Behavioral descriptions only 

Conclusions: 

• Most problems crossing pipeline were confined to fall and early winter migration period when snow 

was absent or light 

• During spring migration, extensive portions of pipeline were drifted over with snow and reindeer 

readily crossed such areas 

• Although some reindeer moved through elevated portals, most animals were deflected 

• Damage to lichen forage adjacent to pipelines occurred due to trampling and overgrazing where animals became concentrated 

• Numerous reindeer became trapped between pipelines until fences were constructed between the 

pipelines to provide corridors to guide animals from elevated loops in one line to elevated loops in the 

opposite pipeline; however, most reindeer still deflected around the pipelines 

• Successful crossings occurred where pipelines crossed ravines and small stream valleys, usually areas 

where pipes were 20 ft or more off the ground 

• Reindeer successfully crossed where pipe was buried or drifted by snow 

• Only ~ 1 /4 of animals that approached pipelines successfully crossed, whereas the rest were deflected 

and entered complexes of mines, smelters, roads, and railroads around the city of Norilsk 

• Plans at the time this report was written included building a fence to divert reindeer completely 

around the Norilsk area, meaning reindeer would be diverted 100 mi or more before resuming their 

normal migration 

Johnson, C. B., and B. E. Lawhead. 1989. Distribution, movements, and behavior of caribou in the 

Kuparuk oilfield, summer 1988. Final report prepared for ARCO Alaska, Inc. and Kuparuk River Unit, 

Anchorage, by Alaska Biological Research, Inc., Fairbanks. 71 pp. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• 11 June to 10 August 1988 

Pipeline Characteristics: 

• Elevated pipelines, mostly closely paralleling roads in Kuparuk Oilfield 

• Crossing structures included ramps and some areas of pipeline/road separation 

• Some areas had multiple pipelines (feeder lines) running parallel to one another 

Study Design: 

• Behavioral observations conducted from pickup trucks during systematic road surveys before insect 

emergence, then using focal-group sampling after insect emergence; conducted by 1 to 2 observers 

between 06:30 and 24:00 

65 
• Entire Kuparuk Oilfield road system west of junction of Milne Point and Spine roads 

• Before insect emergence, surveys conducted every 3 days because movement rates of caribou were 

low 

• Caribou within 1 km of roads were recorded 

• Crossing behavior was recorded both opportunistically and during instantaneous-scan sampling 

• Groups were considered to have crossed a corridor successfully if >50% of individuals in group 

crossed 

• Caribou groups were considered to have attempted to cross a corridor if one or more caribou in the 

group crossed; thus, if no members of a group crossed, the group was not included in calculations of 

crossing success; this definition was considered more a measure of group cohesion during crossings 

than a measure of crossing success in the sense used in other North Slope mitigation studies 

• Number of deflections were recorded and defined as obvious changes in direction within 100 m of a 

corridor; these groups were tallied but were not included in calculation of crossing success 

Objectives: 

• Describe distribution of caribou in parts of the oilfield, including number, density, sex/age composition, and distance from facilities experiencing different levels of human activity, during periods of 

little or no movement (before insect emergence) 

• Quantify activity budgets and movement rates of focal groups of caribou among different insect and 

disturbance conditions and evaluate indicator variables for disturbance 

• Describe movements of focal groups through the oilfield, focusing on crossing success of linear structures, overt responses to disturbance, and rates of movement 

• Describe size, composition, and movements of large aggregations forming during the insect season, 

with specific regard to their responses to oilfield facilities and activities 

Only the third objective, which relates to the crossing success of caribou encountering linear structures, 

is summarized in this annotation 

Data Quantity: 

• 198 crossings of linear structures (pipelines and/or roads) were recorded, involving 179 groups totaling 35,403 caribou 

Analytical Methods: 

• Descriptive statistics of caribou crossing success (group cohesion) 

Results: 

66 

• Proportions of group types observed crossing were 44% cow/calf, 24% bull, 28% mixed, 3% cow/ 

yearling, and <1 % unclassified 

• Crossings of corridors occmTed more frequently during insect harassment than prior to insect emergence 

• Prior to insect season, 9 of 33 (27%) groups crossed at least one corridor during observations, compared to 90 of 196 (46%) groups crossing during the insect season 

• 33% of crossings during the insect season occurred during mosquito harassment, 22% during oestrid 

fly harassment, I 0% during simultaneous mosquito and oestrid fly harassment, and 35% during periods of no insect activity 

• Overall crossing success (cohesion) was high, at 82% of groups and 83% of total individuals, respectively 

• Cow/calf groups were most successful during simultaneous harassment by flies and mosquitoes and 

least successful during mosqLLito harassment 

• Mixed groups, which contained many calves, were most successful during mosquito harassment and 

least successful during insect-free conditions 

• Bulls were more successful under insect-free periods than when harassed by mosquitoes 

• Except for cow/calf groups not harassed by insects, groups crossing corridors without pipelines were 

more successful than those crossing corridors with pipelines 

• Deflections were most common during mosquito harassment, \Vith cow/calf groups deflecting most 

often during this period as well as during all insect conditions combined 
• No deflections occurred at corridors without pipelines 

• Overall crossing success for all groups was nearly identical among all insect conditions ranging from 

79-84% for groups and 80-86% of individuals 

• No deflections were noted during periods of simultaneous harassment by mosquitoes and flies 

• For all insect conditions combined, groups of <10 individuals had highest crossing success (93% of 

groups and 92% of total individuals) 

• For most group-size categories, crossing success tended to be lower during insect-free periods and 

higher during mosquito or simultaneous mosquito and fly harassment 

• Crossing success for individuals in groups of> 1,000 caribou was lowest during insect-free periods 

and highest during mosquito harassment 

• Regardless of insect conditions, crossing success for all size categories was highest at corridors without pipelines 

• 114 of 152 crossing attempts occurred where 1-5 pipes were present; no objective way was identified 

to analyze use in relation to availability of various categories of number of adjacent pipelines 

• Individual and group success were slightly higher where 6-10 pipes were present versus 1-5 pipes; 

may be artifact of small sample sizes 

• No crossings of 11-15 adjacent pipelines were observed except a few that occurred during fly harassment; one attempt at crossing 16-19 adjacent pipes was unsuccessful 

• 71 % of deflections were at sites with 1-5 pipes, 25% occurred at sites with 6-10 pipes 

• Separation of roads and pipelines did not seem to influence crossing success during insect-free 

periods 

• Deflections were high at separation distances of 100 m or less, especially during mosquito harassment 

• Most groups crossing corridors crossed only one (83%) corridor; 17% of groups attempted to cross 

more than one; one group crossed as many as 8 corridors 

• 80% of multiple corridor crossings were observed during periods of insect harassment 

• No crossings of >2 corridors were observed during insect-free conditions 

Data indicated that groups crossing more than one corridor had more difficulty crossing the first few, 

but that subsequent crossings became easier 

• 12 crossings oframps were recorded, involving caribou from 10 separate groups; half of these crossings occurred during periods without insect harassment 

• A group of 3,384 caribou was observed crossing near a ramp during insect-free conditions; 69% of 

group members successfully crossed the pipeline; 2% crossed the ramp 

• A group of 1,815 caribou was observed crossing near a ramp during mosquito harassment; 99% of 

group members successfully crossed the pipeline; <3% crossed the ramp 

• Two groups of 89 and 560 caribou were observed crossing near ramps under simultaneous mosquito 

and fly harassment; all members of both groups crossed; 44 % and 1 % of those groups, respectively, 

crossed the ramps 

Conclusions: 

• Large caribou groups were able to cross road corridors successfully, but reductions in size were common as portions of groups deflected or delayed crossings long enough to prevent them from rejoining 

their groups, possibly increasing their exposure to insect harassment 

• Successful arrival of caribou at insect-relief habitat may have important energetic benefits, especially 

to lactating cows 

• Very little use of gravel crossing ramps was observed 

• During mosquito harassment, approximately I of every 5 groups successfully crossed more than one 

corridor 

• Both measures of crossing success (based on groups and on total caribou) were high, averaging 80% 

( range 54-100%) among various group types and sizes under different insect conditions 

• Adverse behavioral reactions, deflections, delays lasting several minutes to several hours, and splitting of groups were common during crossings of pipeline/road corridors, especially crossings along 

the Spine Road and Oliktok Point Road, both of which had high traffic levels 

67 
• Effects of oilfield activities and facilities on the distribution and movements of caribou were most 

pronounced during insect-free periods; however, in the absence of high traffic, sensitivity of caribou 

to oilfield activities and facilities decreased under the influence of insect harassment 

Peer Reviewed: No 

Klein, D.R. 1971. Reaction of reindeer to obstructions and disturbances. Science 173: 393-398. 

Study Location/Herd: 

• Scandinavia; Norway; Sweden; Finland; various domestic and wild reindeer herds 

Dates of Study: 

• No specific study dates 

Pipeline Characteristics: 

• This review does not specifically mention pipelines, but discusses other linear features such as roads, 

railways, and fences 

Study Design: 

• Information based on personal trips to Scandinavia in 1965, 1967, 1970 

• Conversations with Lapp reindeer herders, government consultants, advisors to reindeer herders, 

biologists, and government officials 

• Includes information from printed reports and publications 

Objectives: 

• Provide a basis for anticipating the problems that may be encountered by caribou exposed to industrial developmentin North America, including highways, railways, hydroelectric developments, 

forestry, fences, snowmobiles, and air pollution and lichens 

• Only reactions to linear structures are included in this annotation 

Data Quantity: 

• 4 personal communications, 7 published papers and reports 

Analytical Methods: 

• Personal observations and interviews 

Results: 

• Highways transect domesticated reindeer ranges throughout Scandinavia and have not been reported 

to significantly interfere with movements except under special circumstances 

• In Norway, well-traveled highways and railroads may have obstructed the movements of a herd of 

wild reindeer between summer and winter range; after a highway and railroad bisected the range, herd 

continued to use areas on both sides of the transportation corridor for a few years, but as train traffic 

increased, reindeer ceased to migrate through the corridor; reindeer milled around near tracks for long 

periods and were repeatedly frightened away when trains passed 

• Reindeer in poor body condition may be easily disrupted and abandon traditional ranges, whereas 

healthy animals are more likely to adjust to disturbance 

• Feeding reindeer did not seem disturbed by highways with traffic 

• 2-m-high fences are used to direct reindeer movements because the animals tend to parallel fences; 

some reindeer are reluctant to be forced into large herds in unfamiliar terrain, so fences must be used 

in conjunction with traditional patterns of movement 

• Also summarized reindeer reactions to hydroelectric development, forestry, and snowmobiles, and 

discussed effects of air pollution on lichens 

Conclusions: 

• In general, highways and railways in Scandinavia have not created barriers to movements by domestic reindeer, but many are struck and killed by vehicles 

• Construction of a railway adjacent to a highway caused some disruption of movements by wild reindeer in Norway 

Peer Reviewed: Yes 

68 
Klein, D. R. 1980. Reaction of caribou and reindeer to obstructions-A reassessment. Pages 519-527 in 

E. Reimers, E. Gaarc, and S. Skjennebcrg, editors. Proceedings of the Second International Reindeer/ 

Caribou Symposium. 17-21 September 1979, Roros, Norway. Direktoratet for vilt og ferskvannsfisk, 

Trondheim, Norway. 

Study Location/Herd: 

• Alaska; N011h Slope; Russia; Siberia; Norway; Prudhoc Bay; wild reindeer; Central Arctic Herd 

Dates of Study: 

• Late 1960s-early 1970s 

Pipeline Characteristics: 

• Norilsk-Messoyakha natural gas pipelines in Taimyr region ofnorthcentral Russia 

• Low-elevation pipelines set on wooden suppmts; height to top of pipes ~ 1 m above ground; diameter 

0.7 m 

• Two parallel pipelines, ~ 1-2 km apart, also paralleling highway and railway 

• Crossing strnctures included wooden ramps and underpasses elevated 3-6 rn above ground, 75-100 m 

in length 

• Lead fences were constructed to guide animals to crossings; fences also constructed to lead animals 

unsuccessful in crossing away from the pipeline and the area sun-ounding Norilsk 

• Trans-Alaska pipeline, elevated, diameter and height unspecified (but see annotations of Cameron and 

Whitten 1976, 1977, 1978; Eide et al. 1986; Carruthers and J akimchuk 1987) 

• Various simulated elevated pipelines, diameters and heights unspecified (but see annotations of Child 

1973, 1974, 1975; Child and Lent 1973) 

Study Design: 

• Literature review 

Objectives: 

• Summarize existing literature concerning reactions of caribou and reindeer to railways, roads, hydroelectric development, and pipelines 

• This annotation addresses pipeline infonnation only 

Data Quantity: 

• Literature rcviev,' 

Results: 

• Norilsk-Mcssoyakha pipeline was complete barrier to wild reindeer, except where it crossed ravines 

or streams or where covered by snow drifts 

• During spring migration, some herds were able to cross the adjacent road and railroad, but ran parallel 

to the pipeline until they found areas to cross that were drifted over by snow or where ravines were 

deep enough to cross under the pipeline 

• One survey in May showed 20,000 reindeer (herd -100,000 animals), mostly pregnant cows, milling 

near stiuctures 

• Train traffic was reduced to minimum during night homs, which helped some reindeer cross; however, many groups, mostly bulls, failed to cross 

• After completion of second pipeline, lead fences were built between pipelines to guide caribou and 

provide access to crossing structures, but only ~25% of caribou were successful in crossing pipelines 

• 54 km of fence eventually was built to guide caribou completely around these structures and the city 

of Norilsk 

• Rangelands east of Yenisei River became largely unavailable to reindeer, but herd continued to grow, 

causing range damage due to extensive overgrazing and trampling in areas adjacent to pipelines 

where reindeer became concentrated 

• Most studies showed general avoidance of Haul Road/TAPS con-idor in northern Alaska by cows with 

calves until the rutting period in the fall, but avoidance seemed to be related more to highway activities than to the pipeline itself 

69 
• Reactions of caribou to the Dempster Highway in Canada were summarized, including effects of traffic speed, quantity, habitat, and height of road berms 

• Author summarizes research carried out near Pmdhoe Bay on the reactions of caribou to a simulated 

low-elevation pipeline (not summarized in this annotation, but see Child 1973) 

• Reindeer on the Seward Peninsula avoided a simulated low-elevation pipeline during winter and summer, only crossing during periods of insect harassment (see Child and Lent 1973) 

• Caribou tend to follow trails packed in snow by vehicles, such as seismic exploration lines and snowmachine trails 

Conclusions: 

• Linear stmctures can block, delay, or deflect movements of caribou with effects depending on mode 

of constrnction and degree of alteration of existing te1rnin 

• Elevated pipelines are more visible in open terrain, meaning caribou may react to them sooner than 

to pipelines in forest; caribou cross more easily under elevated pipeline in forested habitat than open 

tundra 

• Human activity, such as traffic level, associated with pipelines and roads is a major factor influencing 

reactions of caribou to human objects 

• Reactions to obstructions vary among seasons of the year; generally females with calves show stronger avoidance than during winter, caribou cross more frequently during insect harassment, spring 

migration, and fall rut 

• Caribou of different sex and ages react differently to obstructions, with adult males appearing to accommodate more rapidly to their presence, and large groups and females with calves showing more 

avoidance 

• Caribou that reside in areas with obstructions are more likely to habituate to their presence than are 

animals that encounter obstructions on a seasonal basis 

• Reactions to obstructions vary among subspecies of caribou, with woodland caribou showing less sociality than tundra forms and making less extensive migrations, which may make them less motivated 

to cross obstructions 

• Local overgrazing may occur in areas near obstructions 

• Population level effects may be seen if obstrnctions preclude access to calving grounds or insect-relief 

areas 

• Obstructions may contribute to increased energetic losses to caribou seeking to travel around obstructions 

Peer Reviewed: Yes 

Klein, D.R. Undated. Ecology and management of wild and domestic reindeer in Siberia. Unpublished 

report of an exchange visit under terms of USA/USSR Environmental Protection Agreement. Project 

V-2 Ecosystems of Northern Regions. 

Study Location/Herd: 

• Russia; central Siberia; Taimyr wild reindeer 

Dates of Study: 

• Late 1960s-early 1970s 

Pipeline Characteristics: 

• Norilsk-Messoyakha natural gas pipelines 

• Low-elevation pipelines on wooden supports; ground clearance 30-50 cm, but >2 m where pipe 

crossed ravines 

• Diameter 70 cm 

• Two parallel pipelines, separated by ~ 1 km 

• Crossing structures consisted of wooden ramps and underpasses elevated 3-6 m above ground 

• 250 km in length 

• Constructed 1968-1969 

70 
Study Design: 

• Report on visit to Siberia to meet with Russian biologists 

• Discussed management and ecology of domestic and wild reindeer 

Objectives: 

• Discuss common interests between Russian and American biologists in management and ecology of 

domestic and wild reindeer 

Data Quantity: 

• Various interviews with Russian officials during 20 August-5 September 1974 

Analytical Methods: 

• Behavioral descriptions only 

Results: 

• This annotation focuses on reindeer and gas pipelines, but author also provides overview of domestic 

reindeer management in Russia, describes reindeer research organizations, describes techniques used 

in reindeer husbandry, and discusses effects of industrial pollution on vegetation. 

• Pipelines transect migration route of portions ofTaimyr wild reindeer herd 

• Problems in crossing pipelines generally restricted to fall; extensive snow drifts in spring allowed 

reindeer to pass over pipes 

• After reindeer were delayed in their movements, wooden ramps were constructed over pipeline, as 

were portals elevated 3-6 m above ground and 7 5-100 m wide 

• Crossing structures were used only by some animals, while most were deflected; lichen forage was 

overgrazed and trampled near pipelines 

• More reindeer successfully crossed pipeline following installation of portals at 30--40 km intervals, in 

addition to natural passages where pipeline was elevated above ravines 

• Many reindeer crossed one pipeline, but were unable to cross the second, becoming entrapped between the two 

• Fences were constructed to lead reindeer from one portal to a corresponding portal on second pipeline 

• After crossing structures were added, only ~25% of reindeer successfully crossed pipelines, with 

many deflecting into city of Norilsk and its mines, smelters, and roads 

• Administration planned to construct two long lead fences, 42 km and 12 km long, to prevent reindeer 

deflected by pipeline from entering Norilsk, because Russian biologists felt little more could be done 

to increase crossing success 

Conclusions: 

• Russian scientists acknowledged that thousands of wild reindeer were deflected by pipelines and that 

there might be long-term consequences as a result; however, their main conclusion was that reindeer 

had successfully adapted to the pipelines because Taimyr reindeer herd continued to grow 

Peer Reviewed: No 

Lawhead, B. E., L. C. Byrne, and C. B. Johnson.1993. Caribou synthesis, 1987-1990.1990 Endicott 

Environmental Monitoring Program Final Report, Vol. V. U.S. Army Corps of Engineers, Alaska 

District. Final report prepared for Science Applications International Corporation, Anchorage, by 

ABR, Inc., Fairbanks. 114 pp. 

Study Location/Herd: 

• Alaska; North Slope; Sagavanirktok River delta; Endicott Project; Central Arctic Herd 

Dates of Study: 

• Postcalving; insect season: 25 June to 31 July 1987-1989; 25 June to 27 July 1990 

Pipeline Characteristics: 

• Elevated pipeline, average height ~ 1.5 m at top of metal pilings (VSMs), diameter unspecified 

• Pipeline 25-30 m adjacent to a road with traffic 

• VSMs spaced at intervals of l 2-14 m 

• Road averaged 10 m wide and 2 m thick, 2: 1 side slopes, with small pullouts located along road 

71 
• Crossing structures were three 30-m-wide ramps, bordered by 60-m-long sections of elevated pipeline 

that gradually decreased in height near the ramp to assist caribou in finding ramps 

Study Design: 

• Behavioral observations conducted from 3 elevated towers, each overlooking a plot 1.6 km long by 

0.8 km wide 

• Behavioral observations from road surveys along the pipeline/road corridor 1-4 times daily 

• Aerial surveys of caribou distribution on the Sagavanirktok River delta using systematic strip-transects during periods of high insect activity 

Objectives: 

• Monitor caribou use of crossing ramps compared to crossings under nearby elevated pipeline, including an assessment of the effects of insects and traffic on crossing frequency 

• Monitor caribou encounters with the pipeline/road corridor between the Endicott security checkpoint 

and the base of the causeway ( ~ 10 km) 

• Monitor the distribution of caribou throughout the development area on the Sagavanirktok River delta 

• Evaluate predictions of environmental impact statement for Endicott Development Project 

Data Quantity: 

• Time spent observing caribou from towers: 72 hr in 1987, 100 hr in 1988, 86 hr in 1989, 76 hr in 

1990 

• Time spent observing caribou along road/pipeline corridor: 196 hr 1987, I 84 hr in 1988, 158 hr in 

1989, 113 hr in 1990 

• Number of caribou observed 1987-1990 during tower observations: 843 groups comprising 11,420 

caribou 

• Number of caribou observed 1987-1990 during road surveys: 2,366 groups comprising 16,116 caribou 

Analytical Methods: 

• Compared pipeline height at crossing locations (used) with pipeline heights (50-cm height categories) 

in study plots (available), using chi-square goodness-of-fit tests 

• Crossing success compared using ratio estimation and multiple regression 

Results: 

72 

• Mosquitoes emerged 8 July 1987, 7 July 1988, 29 June 1989, 19 June 1990 

• Oestrid flies emerged 10 July 1987, 15 July 1988, 11 July 1989, 4 July 1990 

• Each year, periods of no insect activity were recorded 

• Maximum number of caribou observed per day decreased over course of study period: >4,000 in 

1987, 3,100 in 1988, 328 in 1989, and 113 in 1990 

• Caribou fanned large groups of > 100 during periods of mosquito harassment, but formed groups of 

5-7 during fly harassment 

• Number of mosquito-harassment days was similar during all study years; decreased caribou numbers 

in study area during monitoring period was interpreted as an eastward shift in distribution due to factors other than development; the largest numbers of caribou in the study area were observed during 

construction of the Endicott pipeline (highest amount of human activity) 

• Sex/age composition each year was skewed toward bulls 

• Calf:cow ratios varied among years: 74-78 calves:100 cows in 1987, 57-59:100 in 1988, 30-35:100 

in 1989, 35-43: l 00 in 1990 

• Traffic rates were highest in 1987 (final year of construction), averaging 15.4 vehicles/hr 

• Traffic rates decreased to 6. 9 vehicles/hr in 1988, 5.8 vehicles/hr in 1989, and 5.4 vehicles/hr in 1990 

• Traffic rates varied throughout the day, with the highest volume in the morning and afternoon periods 

(06:00-18:00) and the lowest volume during early morning hours (00:00-06:00) 

• In general, the proportion of caribou crossing the pipeline/road c01Tidor was lower at traffic rates 

above median levels; howyver, only in 1987 (when traffic rates were highest) was the difference significant 

• Proportion of caribou crossing in plots when traffic was> 15 vehicles/hr was significantly lower than 

at <15 vehicles/hr 
• Vehicles were the most common source of behavioral disturbance, resulting in moderate or strong 

reactions among caribou, accounting for 75% of events; large vehicles accounted for more than half 

of these reactions 

• Elevated pipeline was the second most common stimulus, with 11 % of caribou exhibiting moderate or 

strong reactions 

• Humans on foot, though rare in study area, elicited immediate disturbance reactions from caribou 

• 8 7% ofreactions occurred within 100 m of pipeline/road corridor 

• 6% of all caribou and 16% of all groups that crossed pipeline/road corridor in plots used ramps, significantly higher than predicted based on availability 

• Mean size of groups crossing ramps was smaller than mean size of groups crossing under elevated 

pipeline 

• Amount of time spent within 400 m of pipeline/road before crossing was similar between caribou using ramps and those crossing under the pipeline 

• Crossings by caribou in different pipe-height categories differed significantly from availability; pipe 

heights <l m were used least, with no evidence of selection of heights above 1.5 m 

• Insect harassment was the primary factor influencing crossings, with the highest proportion of caribou 

crossing during mosquito harassment 

• No consistent trend was seen in proportion crossing among groups of different sizes, but significantly 

higher proportion of groups of> 100 caribou crossed successfully during mosquito harassment (94%) 

than during periods of combined mosquito and oestrid fly harassment (31 % ) 

Conclusions: 

• Although small numbers of caribou used them, ramps were preferred as crossing sites during all insect conditions 

• Whether ramps increased crossing success or simply provided crossing sites for caribou that would 

have crossed under the pipeline had the ramps been unavailable could not be determined; no consistent trends in crossing frequencies were seen in portions of plots with and without ramps 

• Data did not indicate that ramps expedited crossings 

• When traffic rates were high, ramps did not seem to facilitate crossings of the pipeline/road complex 

by large groups 

• Overall, ramps played a minor role in accommodating crossings of the pipeline/road corridor by caribou 

• Amount of previous experience with pipelines, which could not be measured in this study, may have 

been an important factor affecting crossing frequency 

• Harassment by mosquitoes and oestrid flies had the most profound effects on proportion of caribou 

crossing the road/pipeline corridor; proportion crossing increased as group size increased, a significantly different result than was reported by Smith and Cameron 1985a, 1985b 

• During simultaneous mosquito and fly harassment, caribou seemed to react first to mosquitoes by 

quickly approaching the pipeline, but then milling around the elevated gravel road, crossing and recrossing, as if reacting to fly harassment 

• Annual variability in proportion of caribou crossing pipeline/road corridor was high 

• 15 vehicles/hr was considered the threshold above which caribou crossing success of the corridor ,vas 

negatively affected 

• Although caribou avoided crossing areas of pipe < 1 rn above ground, there was no height selection a( 

or above 1 .5 m · 

Peer Reviewed: No 

Miller, F., C. J. Jonkel, and G. D. Tessier. 1972. Group cohesion and leadership response by barrenground caribou to man-made barriers. Arctic 25: 193-202. 

Study Location/Herd: 

• Canada: Northwest Ten-itories; Kaminuriak Herd 

73 
Dates of Study: 

• Spring migration; May 1967 

Pipeline Characteristics: 

• No pipeline, but a corral made of fencing was constmctcd to capture caribou 

• Corral built on a spit ofland in a lake near traditional migratory routes 

• Spit was 700 m long and 110 m wide at head of spit 

• Fencing was 2.8 m high 

• Lower 120 cm was covered with square mesh wire 

• Entrance to corral was 5 m \Vide 

• Barrier fences, height 2.2 m, were built to funnel caribou 

• Dri fl fences, height 1-1.5 m, were erected to direct caribou 

• Snowmachinc trails were laid in a single line from the corral entrance and extended 3 km away from 

corral 

• Several converging lateral trails were laid out to guide caribou onto the main trail leading into the 

corral 

Study Design: 

Behavioral observations conducted from blind 

Objectives: 

• Provide preliminary insight into possible impact of human-made barriers on migrating caribou 

Data Quantity: 

• 6 groups totaling 4 7 caribou 

Analytical Methods: 

• Behavioral descriptions 

Results: 

• First group (2 cows, I calf, 1 yearling) followed snowrnachine trail to corral entrance: lead cow investigated within 3 m of entrance, then crossed drift fence, where she turned abruptly, perhaps catching 

scent of investigators, and led group back the \Vay they came 

• Second group (3 cows and a juvenile) followed snowmachinc trail to entrance, stopped 3 111 from 

entrance, but eventually entered, then escaped when door failed to close properly 

• Third group approached corral without using snowmachine trail: may have been same caribou from 

first and second group as the composition ,vas the same: lead female approached within 30 m of entrance, tightly circled the group, then crossed a drift fence and paralleled a barrier fence 

• Fomth group ( 11 cows and 8 juveniles) did not use snowrnachinc trail for approach; lead cow crossed 

a drift fence and the others followed, then crossed the batTicr fence by cnnvling under the bottom 

cross piece (40 cm high); others followed 

• An observer startled the group and the female jumped between the top and second cross pieces of the 

fence (space between poles \Vas 38 cm and at a height of 180 cm) 

• Observers attempted to herd this group into the corral and in doing so, the lead female jumped the 

barrier fence, breaking the top pole (2.2 m high) and other caribou leapt through that break 

• Fifth group approached within l 25 m of entrance before veering across a drift fence; lead caribou 

eventually led the group under the bottom bar of the barrier fence where the fourth group had crossed 

a few days before 

• Sixth group ( 5 adults and 2 juveniles), traveling along the trail used by fourth group, crossed a drift 

fence and then crossed under the barrier fence 

Conclusions: 

74 

• Caribou were persistent in trying to cross the lake despite the presence of man-made barriers 

• Caribou followed snowmachine trail on an established migration path, but were reluctant to enter 

brush ( where corral was located) 

• Experience with terrain may play an important role in migratory movements 

• Caribou facing barriers may either wait until environmental conditions allow passage, possibly delaying movements, or they can deviate from traditional routes and attempt a new course 
• Delays caused by barriers may prevent cows from reaching calving grounds in time to give birth or 

may cause females to leave calves behind as they migrate to calving grounds 

Peer Reviewed: Yes 

Murphy, S. M. 1984. Caribou use of ramps for crossing pipe/road complexes, Kuparuk Oilfield, Alaska, 

1984. Final report prepared for ARCO Alaska, Inc., Anchorage, by Alaska Biological Research, 

Fairbanks. 61 pp. 

Study Location/Herd: 

• Alaska; Nmth Slope; western Kuparuk Oilfield; U gnuravik River drainage; Central Arctic Herd 

Dates of Study: 

• Calving; postcalving, insect period; 2-28 July 1984 

Pipeline Characteristics: 

• Pipeline elevated; average height at vertical support members 72 in. 

• Pipeline parallel to and 30 ft from road with traffic 

• Crossing structures included 3 ramps that span_ned pipelines and road; 2 of 3 ramps spaced 0.3 mi 

apart 

• Ramps 100 ft wide with 1:20 slope on one end and a 1:10 slope on the other end, 10:1 side berms 

• Ramps 100 by 100 ft, with gravel extensions 100 ft perpendicularly north and south of road 

• South side of 2 ramps were extended 30 ft whereas the berm of the Spine Road served as the northern 

access point of the third ramp 

Study Design: 

• Second year of study (see Murphy and Curatolo 1984) 

• Behavioral observations conducted from 3 towers 

• No set schedule; rather, caribou observed whenever they were in the 5-mi2 study area 

Objectives: 

• Determine caribou crossing frequencies of 2 pipe/road corridors 

• Identify factors influencing crossing frequencies 

• Determine whether ramps increase crossing success of caribou compared to elevated pipelines 

• Evaluate different ramp designs in tenns of minimizing cost and habitat alteration while maximizing 

caribou crossing 

Data Quantity: 

• 27 field days; 94 groups comprising 1,846 caribou, with 87% of caribou being recorded on first 4 days 

of sampling 

Analytical Methods: 

• Chi-square tests were used to test for differences in direction of movement under different insect conditions, and to test for differences in pipeline and road crossing frequencies 

• Successful group crossing defined as >50% of a group crossing the pipeline/road corridor 

• Mapped caribou movements through study area 

Results: 

• Cow-calf groups were the most abundant group type in study area 

• Caribou movements were predominantly to south when no insects were present and to north/northeast 

when insects were present 

• Movement rates were greatest when mosquitoes were present; movements were slower when oestrid 

flies were present, similar to insect-free conditions 

• Traffic levels on Spine Road were high ( 1 vehicle/1.1 min) and were lower on the DS-2D and DS-2X 

access roads (1 vehicle/10 min and 1 vehicle/12 min, respectively) 

• Vehicles were the most common cause of moderate and strong reactions by caribou 

• Over 50% of the caribou that crossed elevated pipelines/roads showed moderate or severe reactions, 

compared to < 10% for caribou using ramps 

• Over 90% of all strong group reactions occurred within 300 ft of pipe/road complexes 

75 
• Crossing frequencies (based on groups and total caribou) were similar to those recorded before pipeline construction 

• Crossing frequencies were greatest at pipe1ine/road complexes with the least traffic 

• 48% of all caribou that crossed the Spine Road used ramps, a significant increase in use compared 

with 1983; however, group crossing frequencies were similar, indicating use of ramps by large groups 

• The DS-2D ramp contributed little to the overall crossing frequency of the DS-2D pipeline/road complex 

• Small gravel extensions installed on the road side of ramps did not appear to increase caribou use of 

ramps compared to those without extensions 

Conclusions: 

• Rigorous evaluation of the effectiveness of ramps was hampered by small sample sizes, but ramps 

elicited fewer strong reactions from caribou than did elevated pipelines 

• Whether ramps increased crossing frequency or simply provided caribou intent on crossing with a 

preferred site remains unsolved 

• Ramps facilitated the crossing of road/pipeline complexes by large groups of caribou, justifying the 

use of ramps as a mitigation strategy in areas where pipelines are not separated from roads 

• The increase in overall crossing frequency compared with 1983 may have been inflated, due to a 

higher percentage of small groups attempting to cross in 1984, differences in traffic patterns, habituation, and the use of a larger study area in 1984 

• Placing ramps in optimal locations was considered a major factor contributing to overall use, which 

may have accounted for the low use of the DS-2D ramp 

Peer Reviewed: No 

Murphy, S. M. 1988. Caribou behavior and movements in the Kuparuk Oilfield: Implications for energetic and impact analysis. Pages 196-210 in R. D. Cameron, J. L. Davis, and L. M. McManus, editors. 

Proceedings of the Third North American Caribou Workshop. 4-6 November 1987, Chena Hot Springs, 

Alaska. Alaska Department of Fish and Game, Juneau. 

Study Location/Herd: 

• A]aska; North Slope; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

0 Summer; 1981 and 1982 

Pipeline Characteristics: 

• Kuparuk Pipeline 

• Elevated, minimum height 1.5 m above ground 

• 5 study sites: pipe-road site, pipe site, river-road site, and 2 control sites 

• Pipe-road site contained the Spine Road with traffic adjacent to the Kuparuk Pipeline; traffic 1 vehicle/4 min 

• Pipe site contained only the Kuparuk Pipeline and an infrequently traveled work road used for occasional maintenance 

• River-road site contained a road with traffic and no pipeline 

• 2 control sites contained neither roads nor pipelines; data from control sites were combined 

Study Design: 

• Behavioral observations conducted from towers 

• No set observation schedule; rather, caribou were observed whenever they were in the study area 

• Groups were considered successful in crossing pipeline/road corridors if >50°1<> of members crossed; 

in control sites, this crossing success refers to frequency of caribou crossings of the northern border of 

plot 

Objectives: 

76 

• Review Curatolo and Murphy ( 1986) and Murphy and Curatolo ( 1987) on effects of pipelines and 

roads on caribou movements and behavior 

• Discuss energetic implications of altered movement patterns and activity budgets 
This annotation focuses primarily on second objective, because both papers reviewed in this study arc 

annotated in this bibliography 

Data Quantity: 

• See individual annotations for Curatolo and Murphy (1986) and Murphy and Curatolo (1987) 

Analytical Methods: 

• Summarized results of Curatolo and Murphy ( 1986) and Murphy and Curatolo ( 1987) 

Results: 

• 66% of caribou entering control sites crossed northern boundaries (hypothetical pipeline), so 34% did 

not cross 

• During insect-free periods and mosquito harassment, group crossing frequency (37% and 31 % , 

respectively) at the pipe-road site was significantly less than expected, but no significant difference 

was found among sites when oestrid flies were present 

• No significant reductions in crossing frequency at pipe site or river-road site 

• When insects were absent, caribou in control plot spent 90% of time in activities involving energy 

intake and assimilation (feeding and lying); mosquito-harassed caribou reduced time spent feeding, 

and time spent lying decreased by nearly 50%, whereas standing, walking, and running increased 

significantly; oestrid fly-harassed caribou spent even less time feeding and more time standing 

• Decreased energy intake and assimilation have greater effects on energy balance than do increases in 

energy expenditure 

• Rate of movement in control sites was significantly different during each insect season; movement 

rates were greatest during mosquito harassment, followed by oestrid fly harassment, and were lowest 

during periods of no insect activity 

• Except for time spent feeding, during periods without insect harassment there were significant differences among sites in daily activities; running was greatest in pipe-road site 

• During periods without insect activity, rates of movement were not significantly different between 

pipe site and controls, but the mean rate in pipe-road site was> 3.5 times greater than in either of the 

other 2 sites 

• Time spent feeding was not affected by disturbance when insects were absent 

• During mosquito harassment, time spent feeding and lying did not differ significantly between pipe 

site and control, but caribou in pipe-road site spent significantly less time feeding and significantly 

more time lying than did caribou at either pipe site or control 

• Movement rates did not differ significantly among sites when mosquitoes were present 

• Under oestrid fly harassment, caribou in pipe site had activity budget nearly identical to those in control site; caribou in pipe-road site spent significantly less time lying and more time running than did 

caribou at less-disturbed sites 

• No significant differences were found in time spent feeding among study areas during oestrid fly 

harassment 

• Movement rates during the presence of oestrid flies differed significantly among study sites, with fastest movement rates occurring in areas of more human disturbance 

• In control sites, distribution of time spent lying by caribou did not differ significantly from expected 

distribution, whereas there was significant deviation in treatment sites 

• At pipe site, 300 m appeared to be the threshold distance at which the clearest differences in behavior 

could be identified 

• At pipe-road site, 600 m appeared to be the threshold distance, indicating the effect of traffic 

Conclusions: 

• Caribou were able to cross elevated pipelines, but were disrupted in crossing attempts by moving 

vehicles 

• Separation of road with traffic from pipelines will enhance crossing success 

• Very high rates of traffic(> l vehicle/min), would likely create a barrier to caribou movements with or 

without an associated pipeline 

• Mosquito harassment did not appear to have an additive or synergistic effect on caribou activity budgets 

77 
• Differences in activity budgets and movement rates among study sites were greatest during insect-free 

periods and, because insects and oilfield disturbance had similar effects on caribou behavior, data collected during insect-free periods may be best for evaluating effects of oilfield disturbance 

• Insects had a greater impact on energy balance of caribou than did oilfield disturbance; time spent 

feeding was not significantly affected by oilfield disturbance when insects were absent 

• Suggestions for future studies included quantifying the frequency and duration of Central Arctic Herd 

caribou encounters with oilfield development and quantifying the extent that habituation may play in 

reducing oilfield impacts on individual caribou 

Peer Reviewed: Yes 

Murphy, S. M., and J. A. Curatolo. 1984. Responses of caribou to ramps and pipelines in the west end 

of the Kuparuk Oil Field, Alaska, 1983. Final report prepared for ARCO Alaska, Inc., Anchorage, by 

Alaska Biological Research, Fairbanks. 41 pp. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk Oilfield; U gnuravik River drainage; Central Arctic Herd 

Dates of Study: · 

• Calving, postcalving, insect seasons; 30 June to 2 August 1983 

Pipeline Characteristics: 

• Elevated to minimum height of 5 ft; mean height at VSMs in study area was ~ 72 in. ( 6 ft) 

• Pipeline parallel to and 30 ft from road with traffic 

• Crossing structures in study area included 2 ramps, 0.3 mi apart, that spanned the pipeline and road 

• Ramps 150 ft wide 

• Each ramp was a 50-ft-long gravel pad extending perpendicularly 20-25 ft from each side of the pipeline/road corridor 

Study Design: 

• Behavioral observations conducted from 2 towers, whenever caribou were present in the 1.2-mi2 

study area 

• Successful group crossing defined as >50% of group members crossing the pipeline; crossing success 

based on total individuals also presented 

Objectives: 

• Determine if ramps increased the crossing frequency of caribou encountering the Kuparnk Pipeline 

• Determine the most effective ramp design for maximizing caribou crossings while minimizing cost 

and habitat alteration 

Data Quantity: 

• 34 field days 

• 1,151 caribou, 82% of which were recorded on 3 days 

Analytical Methods: 

• Used chi-square tests to compare crossing frequency before and after pipeline constrnction 

• Descriptive statistics of ramp use and pipeline height selection 

Results: 

78 

• Cow-calf groups usually were larger than bull groups, with the largest group sizes observed when 

mosquitoes were present and smallest when oestrid flies were present 

• Caribou groups harassed by mosquitoes moved faster than groups under insect-free conditions 

• Very high traffic levels ( 1.3 and 2.4 vehicles/minute) reduced caribou crossing frequency 

• Higher percentage of caribou groups crossed the Spine Road before pipeline construction than afterward 

• 31 % of groups that successfully crossed the pipeline/road conidor used ramps as crossing sites; all 

ramp crossings occmTed when no insects were present 

• Most pipeline/road crossings occurred when oestrid flies were present and caribou were attracted to 

the corridor for insect relief 

• Caribou did not react strongly to pipeline and road when oestrid flies were present 
• When no insects were present, caribou using ramps reacted less strongly than caribou that crossed 

under the pipeline 

• Mean pipeline height crossed by caribou was 72.4 in., compared with mean height of 71.8 in. available in study area; small sample size (IO groups, 3 6 crossings) disallowed statistical testing 

Conclusions: 

• Due to a construction mistake, both ramps were built identically, so planned comparison between 

ramp designs could not be accomplished 

• Rigorous quantitative evaluation of the effectiveness of ramps was hampered by small sample sizes, 

but qualitative evaluation suggested that caribou used ramps more often than would have occmTed if 

selection of crossing sites were random 

• Ramps did not maintain crossing frequencies similar to pre-pipeline levels 

• Poor ramp design may have contributed to low crossing frequency; authors suggested ramps should 

be extended several hundred feet on both sides of the pipeline to intercept caribou paralleling the 

pipeline 

• High traffic levels on the road were considered the most significant factor affecting crossing 

frequency; ramps may not be able to mitigate the impacts of traffic on caribou 

Peer Reviewed: No 

Murphy, S. M., and J. A. Curatolo. 1987. Activity budgets and movement rates of caribou encountering pipelines, roads, and traffic in northern Alaska. Canadian Journal of Zoology 65: 2483-2490. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• Summer; calving; postcalving; insect period; 2 July to 5 August 1981; 4 June to I August 1982 

Pipeline Characteristics: 

• Kuparuk Pipeline 

• Elevated, minimum height 1.5 m above ground 

• 2 experimental (treatment) plots: pipe-road site and pipe site 

• Pipe-road site encompassed the Spine Road with traffic adjacent to the Kuparuk Pipeline 

• Pipe site encompassed the Kuparuk Pipeline and an adjacent, infrequently traveled road used for 

occasional maintenance 

Study Design: 

• Behavioral observations conducted from towers at 2 experimental (treatment) sites, pipe-road and 

pipe site, and 2 control (reference) sites located in relatively undisturbed habitat south of experimental 

sites ( data from control sites were combined) 

• No set observation schedule used; rather, caribou were observed whenever they entered the study area 

• Groups were considered successful in crossing the pipeline if >50% of group crossed (see Curatolo 

and Murphy 1986 and Murphy and Curatolo 1987 for more detailed description of study design and 

methods) 

Objectives: 

• Assess how activity budgets and movement rates of caribou were affected by insects, pipelines, roads, 

and traffic 

• Delineate zones of reaction adjacent to pipelines and roads 

• Describe behavioral differences among different group sizes and types 

Data Quantity: 

• 35 days of observation during 1981 

• 62 days of observation during 1982 

• Observation hours mostly 08:00-20:00 

Analytical Methods: 

• Compiled time budgets for a pipeline site, a site with a pipeline and traffic, and control sites 

• Compared time budgets using Kruskal-Wallis tests 

79 

I 
• Compared proportion of caribou lying down in different distance zones with empirical distribution 

generated using data set and 99 simulations 

Results: 

• Caribou spent 90% of time feeding and lying when insects were absent and traveled at an average 

speed of 0.7. km/hr 

• Caribou spent 61 % of time feeding and lying when mosquitoes were present; walking and running 

composed 28% of activities; mean movement rate was 2.7 km/hr 

• Standing was the dominant activity when oestrid flies were present, constituting 31 % of activities, 

whereas feeding decreased to 4 7% of the daily activity budget; mean movement rate was 1.6 km/hr 

• Amount of time spent in all activity categories (feed, lie, stand, walk, run) varied significantly between periods when insects were absent and when mosquitoes or oestrid flies were present 

• Only time spent feeding and standing differed significantly between periods when mosquitoes were 

present and when oestrid flies were present 

• Rates of movement differed significantly among all insect harassment categories 

• Traffic rate at pipe-road site was 15 vehicles/hr, versus < 1 vehicle/hr at the pipe site 

• In absence of mosquitoes, percentage of time spent lying and standing were nearly equal in pipe site 

and control, but caribou in pipe-road site spent significantly less time lying and more time standing 

• In absence of insects, time spent walking and running differed significantly among all sites, with both 

variables increasing under conditions of greater disturbance 

• In absence of insects, caribou in pipe-road site spent 14% of their time running, versus 3% and 2% in 

pipe site and control, respectively 

• Movement rates in the absence of insects did not differ significantly between pipe site (0.8 km/hr) and 

controls (0. 7 km/hr) 

• When mosquitoes were present, time spent feeding and lying did not differ significantly between 

control and pipe sites, but caribou in the pipe-road site spent significantly less time feeding and more 

time lying 

• Movement rates when mosquitoes were present did not differ statistically among sites 

• When oestrid flies were present, caribou activity budgets did not differ between pipe site and controls, 

but caribou in pipe-road site spent significantly less time lying and more time running 

• Movement rates when oestrid flies were present differed statistically among sites 

• When insects were absent in the controls, no significant differences were found between empirical 

and expected distributions of lying caribou, but there were significant differences in the pipe-road and 

pipe sites 

• Disturbance threshold distance was estimated at 300 m from the pipeline in the pipe site and at 600 m 

from the pipeline/road corridor in the pipe-road site 

• Three categories of disturbance were identified: low disturbance in control sites and pipe site (300-

1,000 m from pipeline); moderate disturbance in pipe site (<300 m from pipeline) and pipe-road site 

(600-1,000 m from pipeline/road); and high disturbance in the pipe-road site (<600 m from pipeline/ 

road) 

Conclusions: 

80 

• Undisturbed caribou in control sites spent 90% of time performing activities associated with energy 

intake and assimilation, a figure similar to other studies 

• When harassed by insects, caribou spent more time engaged in energetically costly activities and less 

time acquiring and assimilating energy 

• Caribou have lowest net cost of locomotion for any terrestrial vertebrate studied to date, so reductions 

in energy intake have greater effects on energy balance than do increases in activities associated with 

energy expenditure 

• Strongest disturbance effects on behavior occmTed within 600 m of the pipeline/road corridor in the 

pipe-road site; outside of the 300 m zone of the pipe site, caribou behaved similarly to undisturbed 

caribou in control sites 

• Insect harassment appeared to disrupt energy intake and assimilation by caribou more than did oilfield 

disturbances 
• Standing was the predominant activity in all study areas when oestrid flies were present 

• Oilfield disturbance did not further reduce feeding time of caribou harassed by oestrid flies 

• Behavioral differences among group types and sizes primarily involved amount of time spent feeding 

and lying, as well as rates of movement 

• Cow/calf-dominated groups and large groups of caribou were most sensitive to oilfield disturbance 

• Large groups had relatively high rates of movement and low crossing success at linear structures 

• Groups of > 10 caribou rested less and traveled faster than smaller groups, even under low disturbance 

conditions, so greater propensity for movement may be a behavioral trait of larger groups, regardless 

of disturbance 

• Time spent feeding by groups of > 10 caribou was unaffected by disturbance, indicating little effect on 

energy intake 

• Moving stimuli, such as traffic, were more disruptive to caribou energetics than were stationary objects like the pipeline 

• Authors concluded that disturbance-induced behavioral changes and subsequent energetic stress 

would be minimal in a properly designed oilfield that incorporates mitigative measures to allow for 

free passage of caribou, and in which density of structures does not exceed levels at which caribou 

can avoid reactive zones most of the time 

Peer Reviewed: Yes 

Noel, L. E., M. J. Nemeth, and B. J. Streever. 2002. Caribou movement in riparian areas crossed by the 

Badami Pipeline, Arctic Coastal Plain, Alaska, summer 2001. Chapter 4 in M.A. Cronin, editor. Arctic 

Coastal Plain caribou distribution, summer 2001. Final report prepared for BP Exploration (Alaska) 

Inc., Anchorage, by LGL Alaska Research Associates, Inc., Anchorage. 

Study Location/Herd: 

• Alaska; North Slope; Prudhoe Bay; Central Arctic Herd 

Dates of Study 

• Summer (postcalving, insect season); 27 June to 16 August 200 I 

Pipeline Characteristics: 

• Badami Pipeline 

• Elevated, height mostly 1.5 m; 3 areas with elevations <1.5 m 

• Pipeline dampeners hanging down 94 cm below pipeline were installed on 4 sections of pipe ( <21 % 

of total pipeline length) 

• Pipeline length 40 km 

• Crossing structures include buried pipelines at river crossings 

Study Design: 

• Behavioral observations based on time-lapse video-camera footage taking pictures at 6-8 second 

intervals 

• Cameras were set up in pairs at riparian tundra without the pipeline, river channel areas without the 

pipeline, riparian tundra with elevated pipeline, and river channels with buried pipeline 

• Groups differentiated by elapsed time of 15~30 seconds 

• Behaviors were recorded according to group 

• Weather data were gathered from remote weather stations and insect activity indices were estimated 

Objectives: 

• Document number, group size, composition, and direction of large mammal movements in riparian 

corridors with and without buried pipeline 

• Document temporal and spatial movement patterns and their relationship to weather conditions 

• Test influence of Badami Pipeline on deflecting caribou movements to buried river crossings and 

adjacent riparian tundi:a 

Data Quantity: 

• 8 cameras at 16 sites recorded for cumulative total of 382 days 

• 1,976 caribou in 134 groups 

81 
Analytical Methods: 

• Used ANOVA to compare number of caribou crossing per day in riverine and tundra sites with pipelines, without pipelines, and with buried pipelines 

• Analyzed the variables area, pipeline, habitat (riverine or tundra), and pipeline by habitat interaction 

• Used a nonparametric sign test to compare the number of caribou per day among camera pairs 

• Did not test differences in number of groups crossing 

Results: 

• Mean group size was 14.7 caribou with 95% confidence interval of 6.88 caribou 

• 47% of groups were single caribou, 33% were 2-10 caribou, 11 % were 11-50 caribou, and 9% were 

>50 caribou 

• 70% of caribou could not be classified by sex and age 

• Classified caribou included 58% bulls, 21 % cows, 20% calves, and 1 % yearlings 

• Mean duration of caribou near cameras was 2.5 minutes, with maximum of 29 minutes for group of 

190 

• Caribou were more likely to be feeding at pipeline sites than at sites without pipeline 

• Grizzly bears, moose, and muskoxen also were observed on video recordings 

• Largest numbers of caribou moved through study area during 16-23 July, accounting for 47% of 

group observations and 86% of individual caribou counted 

• Highest number of caribou observed from 16:00 to 21 :00; caribou movements appeared to increase 

during the day 

• Caribou group size varied among different river sites 

• Group behavior among sites was generally similar 

• Mean daily temperature at river bar weather station (6.60 degrees C) was significantly higher than at 

tundra station (6.36 degrees C) 

• At tundra station, mean daily temper~ture and wind speed were negatively correlated but highly variable 

• Number of caribou per day was positively correlated with mean daily temperature on 20 days when 

direction of travel was primarily northward or southward, but was not correlated with wind speed 

• On 10 days when primary direction of travel was northward, number of caribou per day was positively correlated with wind speed 

• 3 different models were used to predict insect activity, which was predicted to peak between 17 and 

27 July 

• Mean caribou per day at sites with and without pipelines were similar 

• Mean caribou per day was lowest at river channels with pipelines and highest at riparian tundra with 

pipelines 

• No evidence that number of caribou per day differed among river sites 

• Mean number of caribou per day varied most between habitat types, with fewest seen at river channels both with and without pipelines, but effect was not significant 

• Caribou did not seem to be deflected toward buried pipe at river crossings 

• No evidence that numbers of caribou per day differed between river channel sites \Vith and \vithout 

pipeline 

• Although not significant, number of caribou per day at riparian tundra sites \Vas greater at sites with 

pipeline than without 

Conclusions: 

• Caribou may be more likely to cross a river channel without buried pipeline and on tundra with 

elevated pipeline; perhaps artifact of small sample size 

• Crossing differences may be due to habitat differences among sites 

• Data did not suggest the Badami Pipeline was funneling caribou toward buried river crossings 

• Caribou use buried pipeline river crossings and river channels without buried pipelines at similar rates 

Peer Reviewed: No 

82 
Pullman, E. R., and B. E. Lawhead. 2002. Snow depth under elevated pipelines in western North Slope 

oilfields. Final report prepared for Phillips Alaska, Inc., Anchorage, by ABR, Inc., Fairbanks. 19 pp. 

Study Location/Herd: 

• Alaska: North Slope; Kuparuk; Alpine 

Dates of Study: 

• 26-30 March and 17-20 April 2001 

Pipeline Characteristics: 

• Three different areas of elevated pipeline with minimum design height 152 cm 

• Tarn (DS-2L and -2N) pipeline was examined in E-Vv' and N-S sections; 3 adjacent pipes mounted on 

a single pipe rack; diameter unspecified; VSMs spaced at 1 7 m intervals 

• Alpine pipeline: 3 pipes with diameters 24-in., 18-in., 2-in.; mounted on single VSMs at 20-m intervals; on Colville River delta, pipeline on larger-diameter VSMs and at higher elevation than in area 

cast or delta (latter area referred to as Alpine Corridor) 

Study Design: 

• Measured snow depth and ground clearance (pipeline height) at IO stations spaced evenly across 5 

VSM spans (referred to as a sampling segment); at each station, 3 snow-depth and 1 ground clearance 

measurements were taken, for a total of 30 and IO measurements of snow-depth and ground clearance, respectively, for each sampling segment 

• Measurements under pipelines were paired with transects of equal length l 00 m from and parallel to 

each side of pipeline 

• Landform determinations were made from previously mapped terrain units 

• 140-152 cm was considered to be minimum ground clearance necessary to allow snowrnachiners and 

caribou passage under the pipeline, respectively 

Objectives: 

• Measure minimum clearance between elevated pipelines and snow surface 

• Determine influence of physical variables affecting snow depth under and adjacent to pipelines, such 

as teITain type and pipeline orientation in relation to prevailing wind directions 

Data Quantity: 

• 140 and 100 snow-depth measurements for Tarn pipeline (both N-S and E-W orientations) in March 

and April, respectively 

• 30 and 60 snow-depth measurements for the Alpine Corridor in March and April, respectively 

• 60 sno\v-depth measurements for Alpine Pipeline on the Colville River Delta in April; no March sampling clue to inclement weather 

• 70 and 50 ground-clearance measurements for Tarn Pipeline (both N-S and E-W sections) in March 

and April, respectively 

• 30 and 60 ground-clearance measurements for Alpine Corridor in March and April, respectively 

Analytical Methods: 

• Measured snow depth (mean +/- SD) under pipelines and at upwind and dowmvind sites for 3 pipeline locations and different orientations 

• Compared results using analysis of variance (ANO VA) 

Results: 

Snow depth in March: 

• Snow depth along N-S Tam pipeline averaged 33 cm in basins, 37 cm on terraces, and 63 cm in riverine terrain; upwind background depths were 44 cm in basins, 38 cm on terraces, and 31 cm in riverine 

terrain 

• Snow depth along E-W Tam pipeline averaged 35 cm in basins, 32 cm on terraces, and 94 cm in 

riverine terrain; upwind background depths were 21 cm in basins, 28 cm on terraces, and 35 cm in 

riverine terrain 

• Snow depth in Alpine Corridor averaged 37 cm on terraces, 47 cm in riverine areas; upwind background depths were 38 cm on terraces and 49 cm in riverine areas 

83 
84 

• Background depths along N-S Tam pipeline were significantly greater in downwind transects than 

under the pipeline 

• Results confounded by landscape factors such as the location of downwind transects, many of which 

were located near transition areas between basin and terrace landform types, areas that act as snow 

traps 

• Ice road immediately adjacent to VSMs on west side of Tarn pipeline disrupted natural snow accumulation patterns 

• Under E-W Tarn pipeline, snow depths were significantly greater than background levels in all terrain 

groups 

• Under N-S Tarn pipeline, snow depths were less than background levels in basin areas and were not 

significantly different in other terrain groups 

Snow depth in April: 

• Snow depths were only slightly less than in March 

• Snow depth along N-S Tarn pipeline averaged 30 cm in basins and 34 cm on terraces; upwind background depths were 39 cm in basins and 36 cm on terraces 

• Snow depth along E-W Tam pipeline averaged 36 cm in basins and 26 cm on terraces; upwind background depths were 27 cm in basins and 24 cm on terraces 

• Snow depth in Alpine Corridor averaged 49 cm in basins, 31 cm on terraces; upwind background 

depths were 30 cm in basins and 41 cm on terraces 

• Snow depth in Colville River Delta section averaged 23 cm in basins and 19 cm on terraces; upwind 

background depths were 25 cm in basins and 24 cm on terraces 

• On terraces and in basins under E-W Tam pipeline and in basins in Alpine Corridor, snow depths 

under pipelines were significantly greater than upwind background measures 

• On terraces under N-S Tarn pipeline and in thaw basins in Alpine Corridor, snow depths under pipelines were less than upwind background levels 

• Snow depth under the pipeline differed significantly among individual sampling segments along E-W 

Tam pipeline and Alpine Corridor, compared with adjacent background samples 

• Across all study areas, depth of snow under pipelines and in background segments varied significantly 

in April, being greatest under pipeline in Alpine Corridor (39.9 +/- 17.6 cm), intermediate in Tam area 

(31.4 +/-12.1 cm), and least on Colville River Delta (21.1 +/-10.1) 

• Across all study areas, snow depths did not differ significantly between Tam sections and Alpine Corridor (30.2 cm +/-9.8 vs. 35.5 +/- 16 cm), but were significantly greater than on Colville River Delta 

(24.2 +/-10.1 cm) 

• Pipelines oriented parallel to prevailing wind directions tended to have a plume of deeper snow within 

20 m of pipelines 

Ground clearance in March: 

• E-W Tam pipeline clearance averaged 158.4 cm, range 81-286 cm 

• N-S Tarn pipeline clearance averaged 160. 7 cm, range 119-193 cm 

• Alpine Corridor pipeline clearance averaged 169 .4 cm, range 148-218 cm 

Ground clearance in April: 

• E-W Tam pipeline had average clearance of 145. 7 cm, range 94-179 cm 

• N-S Tarn pipeline clearance averaged 173.8 cm, range 81-286 erμ 

• Alpine Corridor pipeline clearance averaged 173 .8 cm, range 118-289 cm 

• Clearance on the Colville River Delta was high, often >3 m (limit of measuring equipment); minimum clearance was 190 cm 

• Snow depth in April was negatively correlated with pipeline clearance 

• In Tam area in April, 70% of sampling segments measured had at least one occurrence of clearance 

< 152 cm within each 100-m transect surveyed; mean clearance height was < 152 cm in 40% of segments; however, 90% of tl}osc segments had at least one clearance height > 152 cm 

• In Alpine corridor, 83% of sampling segments had at least one occurrence of clearance <152 cm; 50% 

of segments surveyed had mean heights < 152 cm 
• No areas of low clearance were observed on Colville River Delta 

• Continuous areas of low clearance occurred along Tam Pipeline, where 20% of segments had clearances entirely < 152 cm 

Conclusions: 

• Snow depth at 59% of March sampling segments and 55% of April sampling segments did not differ 

significantly between pipelines and upwind background levels 

• In both periods, 25% of sites under pipelines accumulated more snow than upwind background 

samples 

• Landform, pipeline orientation with respect to prevailing wind directions, and ground clearance under 

pipelines are local factors that can be used to predict where significant accumulations of snow under 

pipelines might occur 

• Thaw basins under pipelines tended to have greater snow depths than background areas; snow is most 

likely to be trapped along lee side of basins 

• Snow depth varied over relatively short distances, with the lowest accumulation on the Colville River 

Delta 

• In areas where mean pipe clearance was < 152 cm, snow was likely to accumulate to greater depths 

than background levels 

• Snow depth tended to be greatest where pipelines traverse low-lying terrain such as thaw basins and 

riverine areas 

• On Colville River Delta, where pipe height often exceeded 250 cm, there was no evidence of significant snow accumulation above background levels 

• In certain types of terrain, the effective clearance for snowmachiners and caribou ( defined as > 152 

cm) beneath elevated pipelines was compromised 

• In most of the study sections, stretches of reduced clearance were rarely continuous and sufficient 

clearance > 152 cm usually occurred nearby 

Peer Reviewed: No 

Reges, A. E., and J. A. Curatolo. 1985. Behavior of caribou encountering a simulated low-elevation 

pipeline. Final report prepared for ARCO Alaska, Inc., Anchorage, by Alaska Biological Research, 

Fairbanks. 17 pp. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk River floodplain; Central Arctic Herd 

Dates of Study: 

• Postcalving; insect season; 1-28 July 1984 

Pipeline Characteristics: 

• 2.3 km of simulated, elevated pipeline made out of wax-coated cardboard tubes (Sonotube) 

• Diameter of simulated pipe 20 cm 

• Elevated pipe was adjusted to 3 heights during study: 108 cm, 77 cm, 51 cm 

• Also made a combination section by lowering a section of77-cm-high pipe to 36 cm 

• Distance between vertical supports not specified 

Study Design: 

• Behavioral observations conducted from towers, 24 hr/day 

Objectives: · 

• Determine the maximum height of low-elevation pipeline that caribou will cross 

• Determine if the frequency of crossings varies under the presence or absence of mosquitoes and oestrid flies 

Data Quantity: 

• 624 hours of observation (no observations 2 days) 

• 7,178 individuals observed, including 868 cows, 485 calves, 443 yearlings, 4,259 bulls, and 1,123 

unclassified 

85 
Analytical Methods: 

• Chi-square tests were used to compare crossing success at simulated pipeline (set at various heights) 

and hypothetical pipelines (adjacent to pipeline simulation 

• Tests conducted during different conditions of insect harassment 

Results: 

• Caribou crossed the simulated pipeline significantly less often at all heights compared with hypothetical pipeline delineated by stakes 

• Caribou crossed over the simulated pipeline more frequently at lower heights; only 6 of 1,254 caribou 

crossed the pipe at I 08-cm height 

• Despite some significant differences, no consistent trends were found in the frequencies at which 

caribou crossed the 77 cm, 51 cm, and combination 77 cm-36 cm pipes during the presence of mosquitoes and oestrid flies 

• Caribou crossed over the 36-cm section of the combined 77 cm-36 cm pipe more frequently than 

expected under all insect conditions 

• In the absence of insects, 537 caribou crossed at one of the pipeline heights, out of 1,676 caribou that 

approached the simulated pipeline 

• When mosquitoes were present, 353 caribou crossed, out of 1,058 that approached, a nonsignificant 

difference in crossing frequency 

• When oestrid flies were present, 243 caribou crossed the pipeline, out of 550 caribou that approached, 

a significant increaseincrossing frequency; most of these successful crossings were at the 36 cm high 

section of the 77 cm-36 cm combination pipe 

• Caribou generally reacted to the pipeline when within 100 m and usually moved parallel to it within 

20 m for some distance 

• If caribou attempted to cross, they usually did so singly or a few at a time by jumping from a standing 

position 

• Most caribou paralleled the simulated pipe until they reached a terminus and went around it 

Conclusions: 

• J>ipe elevated to J 08 cm seemed to. be a complete barrier to caribou movement 

• None of the lower pipeline presented as much of a barrier, although authors cautioned this relationship could change if pipe diameter were increased 

• Caribou tended to follow the "path of least resistance" 

• Caribou traveled close to the pipeline and seemed to look for crossing sites, so authors concluded that 

caribou may be able to learn to cross over single pipelines lower than 108 cm 

• Ramps may be useful crossing structures at multiple parallel pipelines or if a greater-diameter pipe 

affects caribou crossing success 

Peer Reviewed: No 

Shideler, R. T. 1986. Impacts of lluman developments and land use on caribou: A literature review. 

Volume II. Impacts of oil and gas development on the Central Arctic Herd. Technical Report No. 86-3. 

Alaska Department of Fish and Game, Juneau. 128 pp. · 

Study Location/Herd: 

• Alaska; Canada; Russia; North Slope; Central Arctic Herd; Taimyr wild reindeer herd 

Dates of Study: 

• Mostly summer studies; calving; postcalving; insect seasons 

Pipeline Characteristics: 

• Various studies are discussed in this review, but pipeline characteristics are not described in detail 

Study Design: 

• Literature review and annotated bibliography 

Objectives: 

• Review history of oil and gas development on the North Slope of Alaska 

86 
• Review features of caribou distribution, movements, abundance, and utilization of specific areas that 

may affect caribou interactions with oil development 

• Discuss impacts of direct habitat loss, harassment by aircraft, vehicles, or humans, avoidance of development, disruption of movements, and increase in predators or human harvest 

This am1otation only discusses pipelines and potential effects on caribou movement 

Data Quantity: 

• Cited 120 references, of which 40 were annotated 

Analytical Methods: 

• Literature review 

Results: 

• Reindeer and caribou reactions to linear developments, including pipelines, are discussed in the Impacts section of the review 

• Movements by Taimyr reindeer herd were disrupted by Norilsk-Messoyakha natural gas pipelines in 

Siberia (not summarized in this annotation, but see annotations for Hemming, undated; Klein, undated, 1980; Skrobov 1972 for more details) 

• As of 1985, Taimyr herd did not migrate across Yenisei River valley as it did prior to pipeline construction; however, this herd continued to increase in size 

• Case history of a railroad and road disrupting the migration of a Norwegian caribou herd was discussed ( see annotation for Klein 1971) 

• Studies showing avoidance of linear developments were discussed, focusing on Trans-Alaska Pipeline; Prudhoe Bay, Kuparuk, and Milne Point oilfields 

• Author reviewed studies addressing the possibility of linear developments (pipelines, seismic lines, 

gravel roads, and highways) disrupting caribou movements 

• This review focused heavily on studies such as Child 1973, Child and Lent 1973, Fancy 1982, Fancy 

1983, Fancy et al 1981, Curatolo 1984, Curatolo and Murphy 1983, Curatolo et al 1982, Murphy 

1984, Smith and Cameron 1985a and 1985b (all of which are annotated separately in this bibliography) 

• Studies were summarized in categories focusing on roads only, pipelines only, and pipelines associated with roads with traffic 

Conclusions: 

• Identified general ranking of severity of human disturbance in terms of effects on crossing success by 

caribou, with least severe being an isolated road with little or no traffic and the most severe being a 

road with traffic adjacent to a pipeline 

• Roads with traffic averaging 15 vehicles/hr were associated with lower crossing success during midsummer 

• Season appears to affect crossing success, perhaps due to changes in group composition or presence 

of insects 

• Type and intensity of insect harassment influences crossing success 

• Suggestions for future study include relating paralleling behavior of caribou attempting to cross pipeline with energetic costs to individuals 

Peer Reviewed: No 

Skrobov, V. D. 1972. Man and the wild reindeer on Taimyr. Priroda 72[3]: 98-99. 

Study Location/Herd: 

• Russia; Siberia; Taimyr reindeer herd 

Dates of Study: 

• 1967-1970 

Pipeline Characteristics: 

• Norilsk to Messoyakha natural gas pipeline 

• Elevated ~40 cm above ground; total height to top of pipe ~ 1 m 

87 
• Pipeline placed on wooden supports 

Study Design: 

• An account of behavioral observations 

Objectives: 

• Describe behavior and movement of wild reindeer near Norilsk pipeline 

Data Quantity: 

• General observalions of spring and fall migration during 1969-1970 

Analytical Methods: 

• Behavioral observations 

Results: 

• \Vile! reindeer usually avoided city of Norilsk, but in 1967 thousands came through and attracted more 

than 6,000 domestic reindeer; these animals crossed the railroad, highway, and water pipeline, resulting in loss of many calves 

• By spring of 1969, gas pipeline from Messoyakha to Norilsk was completed 

Large groups of reindeer accumulated on banks of Yenisei River near gas pipeline 

• Heavy vehicle and train tratYic prevented reindeer from crossing corridors 

• Some crossed road, but were unable to cross pipeline and instead paralleled it from east to west until 

they found an area blown over with snow or where ravines were deep enough to cross under pipeline 

During one aerial survey in May, up to 20,000 reindeer were found milling around hLlman-madc 

barriers 

• Traffic along railroad was reduced to night hours to facilitate movements by reindeer, but some herds, 

mostly bulls, wandered south of railroad in June 

• Some reindeer remained south of pipeline and railroad for summer 

• Poaching occurred involving reindeer groups that accumulated near structures 

• Reindeer avoided migrating over roads and pipelines and near industrial facilities during fall 1969 

and the following spring 

• In fall 1970, some reindeer approached the gas pipeline near Dudinka, but then followed the banks 

of the Yenisei River along the same route used in 1969; small groups remained north of pipeline for 

winter 

Conclusions: 

• Reindeer were able to change their behavior to reach summer and winter pastures despite obstacles 

Peer Reviewed: Yes 

Smith, W. T., and R. D. Cameron. 1985a. Factors affecting pipeline crossing success of caribou. Pages 

40-46 in A. M. Martell and D. E. Russell, editors. Caribou and Human Activity: Proceedings of the 

First North American Caribou Workshop. 28-29 September 1983, Whitehorse, Yukon. Canadian Wildlife Service Special Publication, Ottawa. 

Study Location/Herd: 

• Alaska; North Slope; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• Late spring; early summer; 1981 to 1982 

Pipeline Characteristics: 

• Kuparuk Pipeline 

• Elevated to minimum height of 1.5 m, increasing to >2 mat creek and river crossings 

• 45-cm diameter 

• VSMs spaced at 20-m intervals 

• Depending on location, 1-2 flow lines paralleled the Kuparuk Pipeline 

Study Design: 

88 

• Road surveys conducted by pickup truck twice daily along the West Sak Road (WSR; later called 

Spine Road) 
• Road transect totaled 32 km, including 10 km of road only and 22 km of road paralleled by pipeline 

• Groups were observed until termination of initial crossing episode (not defined further) 

• Successful group crossing was considered to have occurred when 100% of group members crossed 

pipeline/road corridor 

• Authors rep011 on frequency of crossing attempts, but provide no definition of the term 

Objectives: 

• Discuss relative importance of factors affecting crossing success of caribou beneath elevated pipelines, including group size and composition, topography, insect activity, traffic levels, intensity of 

road or pipeline construction activities 

Data Quantity: 

• In 1981, observed 14,148 caribou in 1,120 groups during 86 surveys 

• In 1982, observed 9,523 caribou in 776 groups during 95 surveys 

Analytical Methods: 

• Descriptive statistics; compared crossing success using chi-square tests 

Results: 

• 1981 mean calf percentage in study area (17.6%) was lower than that obtained during regional composition counts (27%) 

• In 1981, most caribou were in groups >40 animals, with <5% of groups accounting for 54% of all 

caribou seen 

• In 1982, group size again was large, with <8% of groups accounting for 65% of all caribou seen 

• Crossing frequency of individuals decreased with increasing group size in 1982, but not in 1981; 

however, 1981 data included one group of 91 7 individuals that was successful in crossing after attempting to cross for 5-6 hr (see Smith and Cameron 1985b) 

• Although fewer caribou groups were seen trying to cross WSR in 1982, percentage of successful 

groups was similar to 1981, but fewer individuals successfully crossed in 1981 than in 1982; differences in number of groups seen trying to cross may have been due to single group of 636 caribou in 

1981 

• Fewer total caribou were seen and fewer crossing attempts were recorded in 1982 during precalving 

and calving periods than during any other period in either year 

• Many crossing attempts by cows with calves were seen during the mosquito season in both years, 

perhaps due to greater movement rates through the areas as caribou attempted to access relief habitat 

north of WSR, leading to more contact with the pipeline/road 

• Average group size during the mosquito season was an order of magnitude greater than during oestrid 

fly period 

• Significantly higher percentage of groups successfully crossed pipeline/road corridor during oestrid 

fly period than mosquito period, possibly related to smaller group sizes during oestrid fly harassment 

• In 1982 both individuals and groups were significantly more successful in crossing the pipeline/road 

during oestrid fly harassment than during same period in 1981; low crossing success of individuals in 

1981 possibly attributable to response of single group of 5 8 caribou 

• 30. 7% of caribou in 1981 were recorded during moderate or severe insect harassment, but accounted 

for 93 .2% of crossing attempts 

• 52.3% of caribou in 1982 were recorded during moderate or severe insect harassment, but accounted 

for 97 .2% of crossing attempts 

Conclusions: 

• During oestrid fly activity, fewer caribou use habitats adjacent to WSR, but their ability to negotiate 

roads and pipelines increased 

• Differences in experimental design and definitions of crossing success complicate comparisons 

among studies 

• In this study, authors attempted to relocate caribou that did not initially cross pipeline/road, after 

completing their standard survey; since larger groups were easier to identify and relocate, this method 

might have biased results toward large groups, which had lower crossing success than smaller groups 

89 
Crossing success based on groups may give different results than crossing success based on the total 

number of individuals in those groups; crossing success for an entire group may be zero (using the 

criterion of 100% crossing), but a proportion of individuals may cross 

• Crossing success may be a social response based on time of year, such as during insect season when 

social bonds are more ephemeral, or a functional response to a barrier 

• Crossing success rates at roads alone were significantly higher than at pipeline/road complexes 

• Caribou in this study did cross buried pipe in areas of heavy traflic, likely due to design problems 

such as width <22 m and, in some, openings being partially obscured from view 

• Differences in ramp design, along with ramps associated with varying levels of disturbance throughout a study area, makes it impossible to identify factors that enhance its selection and use 

Little is known about importance of width, steepness of approach slopes, funneling structures, and 

visibility of opening on ramp effectiveness, all of which might affect ramp use; varying amounts of 

tratlic also may affect ramp use 

• Specific crossing sites should be integrated into a regional plan to preserve movement corridors 

through oilfield complexes 

Peer Reviewed: Yes 

Smith, W. T., and R. D. Cameron. 1985h. Reactions of la1·ge groups of caribou to a pipeline corridor on 

the Arctic Coastal Plain of Alaska. Arctic 38: 53-57. 

Study Location/Herd: 

• Alaska; North Slope; Arctic Coastal Plain; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• Summer; insect period; observations from 18 July 1981 and 13 July 1982 

Pipeline Characteristics: 

• Kuparuk Pipeline, elevated to minimum height of 152 cm 

• Diameter 50 cm 

VSMs spaced at 20-m intervals 

• Pipeline closely paralleled roads with different amounts of traffic 

Crossing structures included functional ramps (buried sections of pipe at road crossings) 

Study Design: 

• (See Smith and Cameron 1985a, Smith et al. 1994) 

Objectives: 

• Describe responses by two large, insect-harassed groups of caribou to a road/pipeline corridor between the Kuparuk and Prudhoc Bay oilfields. during the first and second summers after pipeline 

construction 

Data Quantity: 

• 12 and 8 hr of observation on groups of 917 and 655 caribou, respectively 

Analytical Methods: 

• Behavioral observations and descriptive statistics 

Results: 

• Of the group of917 caribou observed on 18 July 1981, 46% crossed under elevated pipeline, without 

recrossing, in 26 attempts; 13% crossed over buried sections in 2 attempts; 22% paralleled the pipeline for at least 32 km without crossing 

• Of the 515 caribou observed on 13 July 1982, 26% crossed under elevated pipeline without recrossing; 37% crossed over a buried section in one attempt; 37% separated from the main group and their 

crossing success could not be detennined 

• Overall, 60% and 64% of the group members crossed the pipeline during the authors' observations in 

the 1981 and 1982 encounters, respectively 

Conclusions: 

90 

• Some caribou in large insect-harassed groups may exhibit difficulty in crossii1g or be prevented from 

crossing elevated pipelines 
• Groups may fracture into smaller groups, potentially exposing individuals to greater degree of mosquito attack 

• Caribou were more successful in crossing buried sections of pipeline, particularly those isolated from 

traffic, compared to elevated pipeline 

Peer Reviewed: Yes 

Smith, W. T., R. D. Cameron, and D. J. Reed. 1994. Distribution and movements of caribou in relation 

to roads and pipelines, Kuparuk Development Area, 1978-1990. Wildlife Technical Bulletin No. 12. 

Alaska Department of Fish and Game, Juneau. 54 pp. 

Study Location/Herd: 

• Alaska; Notih Slope; Kuparuk Oilfield; Central Arctic Herd 

Dates of Study: 

• Spring and summer; late May, June, July, early August; 1978 to 1990 

Pipeline Characteristics: 

• Kuparnk Pipeline ( constructed winter 1980-1981) and feeder pipelines in Kuparuk Oilfield 

• Elevated pipelines (152-cm minimum height), most paralleling roads 

Study Design: 

Systematic road surveys conducted once or twice daily over standardized route by one observer in a 

light truck 

Caribou were observed approaching roads and/or pipelines until the termination of the initial crossing event, generally 5-20 min 

• Crossing success not defined; in earlier reports, authors considered group crossings successful if 

100% of group members crossed during observations 

• Crossing attempts referred to, but criteria were not defined ( e.g., using a specific approach distance) 

• Traffic rate was recorded but not reported or analyzed in relation to crossing success of caribou 

Objectives: 

• Determine chronological changes in distribution, movement patterns, and composition of caribou 

within or near Kuparuk Development Area (KDA) 

• Detennine locations of pipeline and road crossings by caribou 

• Characterize responses of caribou to human structures and disturbance 

This annotation only summarizes the last two objectives as they relate to crossings of linear structures 

Data Quantity: 

• 13 years of seasonal data: precalving (10-25 May), calving/postcalving (1-30 June), midsummer 

(1 July-IO August) 

Analytical Methods: 

• Conducted road surveys along the Spine Road (referred to in their earlier reports as the West Sak 

Road) during 1978-1990 and the Oliktok Point Road during 1982-1990 

• Recorded locations of caribou crossing roads, pipelines, and road/pipeline combinations 

• Reported crossing success by year and group size 

Results: 

Crossings o_f newly constructed roads prior to Kuparuk Pipeline construction (1978-1980): 

• Most crossings occurred during insect-induced movements, although relatively few caribou were 

observed during insect harassment 

• Number of crossings increased annually 

• Number of groups successfully crossing roads increased, but individual crossing success decreased 

• Most crossings in any one year occurred in a single road segment near intersecting stream drainages 

located away from construction activities 

• Only two groups of> 100 caribou were observed trying to cross the road and both were unsuccessful 

Period of initial construction (1981-1984) - Precalving (10-25 May): 

• Numbers of caribou observed crossing road continued to increase, but represented only 1 % of all 

caribou observed 

91 
• Crossing success of roads by individuals was low: 28.5% in 1982, 16.7% in 1983, 44.4% in 1984 

• In 1983 and 1984, 50% and 30.8%, respectively, of individuals crossed pipeline/road corridors successfully 

Period o.f initial construction (1981-1984) - Postcalving (2-30 June): 

• Crossing success during all 3 years was high for groups (100%, 80%, 100%) and individuals (94%, 

95%, and 100%), although in 1981 only 14 of 29 caribou in 2 groups were observed crossing road/ 

pipeline 

Period of initial construction (1981-1984) - Midsummer (1 July-7 August): 

• Oliktok Point Road was added to survey coverage, increasing group and individual crossing success; 

percentage of maternal cows crossing was high 

• Crossing success of groups approaching pipeline/road corridors was 80% 

• Individual success was lower than group success because large groups > 100 animals were more likely 

to be prevented from crossing 

• Both group and individual crossing success tended to be lower for pipeline/road corridors than for 

either roads or pipelines alone 

Periocj of advanced construction (1985-1990) -Precalving (11-24 May): 

• Few caribou were seen attempting to cross pipelines or roads before calving 

• In 1985, 5 of7 groups (11 of28 caribou) crossed successfully during observations 

• In 1986, 5 individuals in a single group of 7 caribou crossed successfully during observations 

Period of advanced construction (1985-1990) - Postcalving (2-20 June): 

• Crossing rates of pipeline/road corridors were low during postcalving 

• Large groups had difficulty crossing pipeline/road corridors 

• Groups had greater crossing success than did individuals 

Period o_fadvanced construction (1985-1990) - Midsummer (1-6 August): 

• Numbers of caribou observed crossing pipeline/road corridors increased until 1988 

• Calf percentage of crossing groups was greater than or equal to annual estimated calf percentages for 

the region 

• In 1986, numbers of individuals and groups, including those containing > 100 caribou, successfully 

crossing pipeline/road corridors increased, but declined thereafter 

• In 1990, crossing success of pipeline/road corridors reached highest levels 

Conclusions: 

Authors made recommendations to mitigate the effects of oilfield development on caribou and suggested 

future studies 

• Continue to discourage development on calving grounds 

• Maintain 3-km-wide zone of minimum surface development along the coast to accommodate mosquito-harassed caribou 

• Discourage additional road construction within the two major crossing areas then used by caribou 

entering and exiting the KDA 

• Minimize "network effect" of KDA by concentrating new support and processing facilities in areas 

already developed 

• Reduce traffic through convoying of vehicles and busing of workers 

• Promote development of technology for pipeline burial and encourage improved design and evaluation of elevated pipelines 

• Give elevated pipelines greater clearance, separate roads from pipelines, and build crossing ramps of 

varying height and length 

• Curtail road surveys during calving due to low sighting rates 

• Continue midsummer surveys to determine distribution and group composition of caribou along road, 

monitor changes in distribution of road/pipeline crossings and crossing success, and obtain estimates 

of midsummer sex/age composition of the western segment of the Central Arctic Herd 

Peer Reviewed: No 

92 
Thompson, D. C., K. H. Mccourt, and R. D. Jakimchuk. 1978. An analysis of the concerns for the Porcupine Caribou Het·d in regard to an elevated pipeline on the Yukon Coastal Plain. Report prepared for 

Dome Petroleum Ltd., by Renewable Resources Consulting Services Ltd. 88 pp. 

Study Location/Herd: 

• Canada; Yukon; Arctic Coastal Plain; Porcupine Herd 

Dates of Study: 

• Various studies prior to 1978 

Pipeline Characteristics: 

• No pipelines built at lime of study, this review addressed possible effects of an elevated pipeline on 

caribou movements 

Study Design: 

Literature review 

Objectives: 

• Review concerns regarding effects of development projects on caribou, based on effects documented 

in literature and expressed as concerns by participants in the Mackenzie Valley Pipeline Inquiry 

• Synthesize information on effects into substantiated concerns for the construction of an elevated pipeline along the Yukon coast 

Data Quantity: 

• Literature review 

Results: 

• Only info1111ation relevant to movements and crossing success of caribou in relation to elevated pipelines is summarized in this annotation 

• Sensitivity of caribou to construction and operation of an elevated pipeline ,vas discussed in relation 

to sensory disturbances, direct mortality (i.e., vehicle collisions). habitat alteration, and interference 

with caribou movement patterns 

• Caribou may avoid or parallel pipelines or avoid pipeline corridors 

• Snowbanks> 1.5 min height prevented caribou from crossing plowed roads 

• Some studies showed a degree of accommodation by caribou to pipelines (see Child 1973); one study 

of winter reactions of caribou to seismic lines found that caribou were deflected by new lines, but 

crossed older ones without hesitation 

• Authors discussed observations of wild reindeer encountering a pipeline in Russia (sec annotated 

references for Klein 1971 and Skrobov 1972 in this bibliography) 

Concerns expressed at public inquiry: 

• If caribou intersect pipeline at approach angles <45 degrees, their movements may be deflected 

• Pipeline might cause disturbance on calving grounds and if a shift were to occur, caribou might suffer 

increased predation by wolves 

• Presence of pipeline may disrupt movements and lead to separation of calves and cows or slower 

rates of movement 

• Many witnesses expressed concern over impacts of pipeline next to a road with traffic and impacts 

associated with hunting from these roads 

• Most expert witnesses rejected the idea of a road across the Yukon coastal plain 

• Limiting pipeline construction during calving may limit disturbance 

• Mitigation measures may include limiting public access to roads associated with pipeline development 

Conclusions: 

• Placement of pipeline as close as possible to coast would reduce interactions with caribou on calving 

grounds and migration routes 

• Access roads should be placed parallel to pipeline and be restricted to right of way as much as possible (note that this recommendation was made before Kuparuk studies revealed negative effects of 

roads with traffic immediately adjacent to pipelines; e.g., see Curatolo and Murphy 1986) 

93 
• Roads should be planned in consultation with biologists who are familiar with distribution and movements of caribou in area 

• Length of access roads should be kept to minimum 

• Ancillary installations should be located away from key areas of caribou range 

• Pipelines should be elevated a minimum of 7-8 ft above ground level to allow passage of caribou; not 

known how much of pipeline should have crossings at this height 

• VSMs should be placed at a maximum distance apart 

• When stringing pipe, pipe should be placed at angle to allow passage of caribou 

• Snow fences located parallel to road should not interfere with caribou movements 

• No pipeline facility should be used as a base for hunting 

• If pipeline were to be abandoned at some point, all structures should be removed and disturbed tundra 

should be rehabilitated 

Peer Reviewed: No 

Whitten, K. R., and R. D. Cameron. 1986. Groups versus individuals as sample units in the determination of caribou distribution. Pages 325-329 in A. Gunn, F.L. Miller, and S. Skjenneberg, editors. Proceedings of the Fourth International Reindeer/Caribou Symposium. 22-25 August 1985, Whitehorse, 

Yukon Territory. Nordic Council for Reindeer Research, Harstad, Norway: Rangifer, Special Issue 

No.1. 

Study Location/Herd: 

• Alaska; North Slope; Central Arctic Herd 

Dates of Study: 

• Winter, spring; calving; postcalving; August; pre-rut; rut 

Pipeline Characteristics: 

• Critique of selected previous studies 

Objectives: 

• Demonstrate how failure to consider variation in group size and composition led to erroneous conclusions regarding differential habitat use by male and female caribou 

Data Quantity: 

• Not specified; focused on critiquing two studies (by Carruthers et al. 1984 along TAPS [not the same 

citation annotated in this bibliography], and by Curatolo 1985 in Kuparuk Oilfield [not the same citation annotated in this bibliography]) 

Analytical Methods: 

• Used selected data from Carruthers et al. (1984) to reassess their conclusions based on total number 

of individual caribou in groups instead of number of groups 

• Calculated percentage of individuals in riparian areas; did not address problems arising from lack of 

independence in statistical tests using individuals. 

Results: 

94 

• Authors compare two studies quantifying habitat use by male and female caribou 

• First study of habitat preference analyzed data based on whether or not groups were male- or femaledominated, based on which gender comprised >70% of the group 

• Second study assigned group gender in a similar fashion, using >67% as the classification percentage; 

that study also analyzed habitat selection data based on individual caribou locations 

• Both studies found that a higher percentage of male groups was found in riparian habitat compared to 

female groups 

• Data from groups can only be extrapolated to populations as a whole if individuals are distributed 

similarly to groups 

• Because female groups tended to be larger than male groups, female caribou in riparian areas may 

still outnumber males, even though a smaller proportion of female-based groups were found in riparian areas compared to male-based groups 
• Based on analysis of individual locations, second study found that caribou consistently preferred 

riparian habitats, both along Trans-Alaska Pipeline (TAPS) and the surrounding area 

• Percentage of calves along TAPS was lower than surrounding region 

• Except during calving, calves were less abundant within or near riparian habitat along TAPS 

• Except during August and pre-rut, calves were less abundant in nonriparian habitat along TAPS 

• No clear evidence from second study, based on individual locations, that females with calves used 

riparian habitat differently from other caribou; rather, all caribou preferred riparian habitat, with cow/ 

calf pairs avoiding all habitat along TAPS 

• Authors claim first study based on group locations did not take into account human disturbance that 

occurs along the Kuparuk river drainage 

Conclusions: 

• Authors assert that data based on groups are not appropriate for describing population distribution or 

habitat preferences of caribou (the statistical need for independence of observations was not acknowledged) 

• Extrapolations based on data analyzed by group yielded different results than data based on individuals composing groups 

• Because caribou groups vary in size and composition, and members of the same sex/age class may 

occur in more than one group type, analyses based on groups alone will not be representative of the 

population 

• Number of individual caribou, not number of groups, should serve as basis for most studies of distribution 

Peer Reviewed: Yes 

Wolfe, S. A., B. Griffith, and C. A. Gray Wolfe. 2000. Response of reindeer and caribou to human activities. Polar Research 19: 63-73. 

Study Location/Herd: 

• Alaska; Norway; Russia; Canada; Nelchina Herd; Central Arctic Herd; woodland caribou; wild reindeer 

Dates of Study: 

• Various, not specified 

Pipeline Characteristics: 

• Trans-Alaska Pipeline 

• Kuparuk Pipeline 

Study Design: 

Literature review 

Objectives: 

• Review literature investigating the responses of reindeer and caribou to human activities 

• Human activities included aircraft, railways, highways, pipelines, recreational activities, and forestry 

practices 

This annotation focuses only on reactions to linear structures (roads, railways, pipelines). 

Data Quantity: 

• 86 studies, including published reports, journals, theses, and conference proceedings 

Analytical Methods: 

• Literature review 

Results: 

• Elevated road berms that pose visual barriers were most strongly avoided by caribou in fall and winter 

• Insect harassment, particularly by oestrid flies, increased the frequency with which caribou of all sex 

and age classes crosse~ roads and other linear infrastructure 

• Roads with no or light traffic did not deter caribou from crossing and had little effect on use of traditional migration routes, distribution, or energetic costs 

95 
• While migrations have continued across railways or roads in Canada, Newfoundland, and Alaska, 

they ceased in Norway after construction of a railway adjacent to a highway 

• Publications reviewed specific to pipeline interactions included Child 1973, Caruthers and Jakimchuk 

1987, Curatolo 1983, Curatolo and Murphy 1986, Eide et al. 1986, Fancy 1983, Hanson 1981, Murphy 1988, Murphy and Curatolo 1987, and Smith et al. 1994, all of which are annotated elsewhere in 

this bibliography; no new information was presented 

• Authors reviewed studies detailing the distribution of caribou near infrastructure, but those studies 

were not specific to caribou crossing success of linear structures and so are not summarized here 

Conclusions: 

Authors listed mitigation measures to facilitate crossings of pipelines by caribou, as suggested by other 

authors (see studies listed above). They also suggested mitigative measures to minimize disturbance 

caused by other infrastructure and aircraft which are not discussed below 

• Involve biologists in project design 

• Minimize traffic and prohibit unnecessary access to oilfields in critical habitats and during critical 

seasons 

• Avoid exploration and construction during calving and postcalving 

• Minimize network effect of road developments 

• Elevate pipelines 1.5 m or higher above ground level and bury pipelines where feasible, especially 

near known caribou crossing areas 

• Separate elevated pipelines from roads with traffic by> 150 m 

Authors discuss effects of disturbance and factors that might affect the ability to detect these effects 

• Population effects of disturbance on caribou are less clear, but reduced density of animals near infrastructure suggests that individual avoidance may accumulate at the population level 

• Animals may be displaced into less desirable habitat, but studies have not <lemonstrated such effects 

of displacement 

• Estimation of cumulative effects of disturbance is necessary to estimate net effects of disturbance 

• For effects to be detectable, cumulative effects must be of consistent direction and exceed natural 

variability within or among herds; however, disturbance may increase variability in distribution or 

population performance rather than alter average measures such as means 

• Effects of disturbance may be affected by annual or seasonal variation in environmental conditions 

• Herds should not be expected to show same sensitivity to reactions as herds occupying low-quality or 

more variable ranges; herds exposed to multiple disturbance types in multiple portions of their range 

may be less resilient to disturbance 

• Estimates of proportions of individuals exposed to disturbance are lacking, making it inappropriate to 

project modeled estimates of energetic costs at the individual level to the population level 

• More empirical and modeling work needs to be done before effects of human disturbance on caribou 

can be assessed fully 

• The most neglected elements of study include identifying mechanisms of cumulative population 

response, estimating exposure of individuals and populations, and modeling population responses to 

disturbance 

Peer Reviewed: Yes 

96